2D/2D heterojunction of Ti3C2/g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution

A Review of Metal-Organic Frameworks Derived Hollow-Structured Photocatalysts: Synthesis and Applications

Photocatalysis is a most important approach to addressing global energy shortages and environmental issues due to its environmentally friendly and sustainable properties. The key to realizing efficient photocatalysis relies on developing appropriate catalysts with high efficiency and chemical stability. Among various photocatalysts, Metal-organic frameworks (MOFs)-derived hollow-structured materials have drawn increased attention in photocatalysis based on advantages like more active sites, strong light absorption, efficient transfer of pho-induced charges, excellent stability, high electrical conductivity, and better biocompatibility. Specifically, MOFs-derived hollow-structured materials are widely utilized in photocatalytic CO2 reduction (CO2RR), hydrogen evolution (HER), nitrogen fixation (NRR), degradation, and other reactions. This review starts with the development story of MOFs, the commonly adopted synthesis strategies of MOFs-derived hollow materials, and the latest research progress in various photocatalytic applications are also introduced in detail. Ultimately, the challenges of MOFs-derived hollow-structured materials in practical photocatalytic applications are also prospected. This review holds great potential for developing more applicable and efficient MOFs-derived hollow-structured photocatalysts.

Unveiling the photocatalytic potential of graphitic carbon nitride (g-C3N4): a state-of-the-art review

Graphitic carbon nitride (g-C3N4)-based materials have emerged as promising photocatalysts due to their unique band structure, excellent stability, and environmental friendliness. This review provides a comprehensive and in-depth analysis of the current state of research on g-C3N4-based photocatalysts. The review summarizes several strategies to improve the photocatalytic performance of pristine g-C3N4, e.g., by creating heterojunctions, doping with non-metallic and metallic materials, co-catalyst loading, tuning catalyst morphology, metal deposition, and nitrogen-defect engineering. The review also highlights the various characterization techniques employed to elucidate the structural and physicochemical features of g-C3N4-based catalysts, as well as their applications of in photocatalytic degradation and hydrogen production, emphasizing their remarkable performance in pollutants' removal and clean energy generation. Furthermore, this review article investigates the effect of operational parameters on the catalytic activity and efficiency of g-C3N4-based catalysts, shedding light on the key factors that influence their performance. The review also provides insights into the photocatalytic pathways and reaction mechanisms involving g-C3N4 based photocatalysts. The review also identifies the research gaps and challenges in the field and presents prospects for the development and utilization of g-C3N4-based photocatalysts. Overall, this comprehensive review provides valuable insights into the synthesis, characterization, applications, and prospects of g-C3N4-based photocatalysts, offering guidance for future research and technological advancements in this rapidly growing field.

Ultrathin 2D/2D ZnIn2S4/La2Ti2O7 nanosheets with a Z-scheme heterojunction for enhanced photocatalytic hydrogen evolution

Layered lanthanum titanate (La2Ti2O7) perovskite is a good photocatalytic material owing to its high stability, strong redox ability, and non-toxicity. However, its inherent wide bandgap limits its application in photocatalytic hydrogen evolution. Therefore, combining La2Ti2O7 with two-dimensional (2D) narrow-bandgap semiconductors to form 2D/2D layered structures is the preferred strategy to improve its photocatalytic performance. In this study, a novel 2D/2D ZnIn2S4/La2Ti2O7 Z-scheme heterojunction was prepared through a solvothermal method. The experimental results show that when the molar ratio of La2Ti2O7 to ZnIn2S4 is 1 : 4, the hydrogen evolution rate of the composite under ultraviolet-visible light reaches 6.97 mmol g-1 h-1, which is 3.5 times higher than that of the pure ZnIn2S4. The results of the morphological characterization studies of the samples and the photoelectrochemical measurements show that channels for the rapid transfer of carriers are generated by the unique 2D/2D structure of these samples, and the separation and migration efficiency of the photogenerated carriers significantly improved due to the formation of the Z-scheme heterojunction. This study provides useful insights into the modulation of wide-bandgap semiconductors and research into solar energy conversion.

Advancing lithium-sulfur battery efficiency: utilizing a 2D/2D g-C3N4@MXene heterostructure to enhance sulfur evolution reactions and regulate polysulfides under lean electrolyte conditions

Lithium-sulfur batteries (LSBs) show promise for achieving a high energy density of 500 W h kg-1, despite challenges such as poor cycle life and low energy efficiency due to sluggish redox kinetics of lithium polysulfides (LiPSs) and sulfur's electronic insulating nature. We present a novel 2D Ti3C2 Mxene on a 2D graphitic carbon nitride (g-C3N4) heterostructure designed to enhance LiPS conversion kinetics and adsorption capacity. In a pouch cell configuration with lean electrolyte conditions (∼5 μL mg-1), the g-C3N4-Mx/S cathode exhibited excellent rate performance, delivering ∼1061 mA h g-1 at C/8 and retaining ∼773 mA h g-1 after 190 cycles with a Coulombic efficiency (CE) of 92.7%. The battery maintained a discharge capacity of 680 mA h g-1 even at 1.25 C. It operated reliably at an elevated sulfur loading of 5.9 mg cm-2, with an initial discharge capacity of ∼900 mA h g-1 and a sustained CE of over 83% throughout 190 cycles. Postmortem XPS and EIS analyses elucidated charge-discharge cycle-induced changes, highlighting the potential of this heterostructured cathode for commercial garnet LSB development.

Recent progression in MXene-based catalysts for emerging photocatalytic applications of CO2 reduction and H2 production: A review

The development of advanced materials for efficient photocatalytic H2 production and CO2 reduction is highly recommended for addressing environmental issues and producing clean energy sources. Specifically, MXenes have emerged as two-dimensional (2D) materials extensively used as high-performance cocatalysts in photocatalyst systems owing to their outstanding features of structure and properties such as high conductivity, large specific surface area, and abundant active sites. Nevertheless, there is a lack of deep and systematic studies concerning the application of these emerging materials for CO2 reduction reaction (CRR) and H2 production (HER). This review first outlines the essential features of MXenes, encompassing the synthesis methods, composition, surface terminations, and electronic properties, which make them highly active as cocatalysts. It then examines the recent progress in MXene-based photocatalysts, emphasizing the synergy achieved by coupling MXenes as co-catalysts with semiconductors, utilizing MXenes as a support for the consistent growth of photocatalysts, leading to finely dispersed nanoparticles, and exploiting MXene as exceptional precursors for creating MXene/metal oxide photocomposite. The roles of engineering surface terminations of MXene cocatalysts, MXene quantum dots (QDs), and distinctive morphologies in MXenes-based photocatalyst systems to enhance photocatalytic activity for both HER and CRR have been explored both experimentally and theoretically using DFT calculations. Challenges and prospects for MXene-based photocatalysts are also addressed. Finally, suggestions for further research and development of effective and economical MXenes/semiconductors strategies are proposed. This comprehensive review article serves as a valuable reference for researchers for applying MXenes in photocatalysis.

Facile Fabrication of Titanium Carbide (Ti3C2)-Bismuth Vanadate (BiVO4) Nano-Coupled Oxides for Anti-cancer Activity

Background MXene is a newly discovered substance consisting of 2D transition metal carbides or nitrides, produced through the disintegration and etching of aluminum layers. It possesses numerous properties, including a high surface area, conductivity, strength, stiffness, negative zeta potential, and excellent volumetric capacitance. MXene is utilized in detecting anti-cancer medicine, while bismuth vanadate (BiVO4) is synthesized to form an optimized material for anti-cancer activity applications. BiVO4 exhibits visible light absorption, strong chemical stability, and non-toxic properties. However, when loaded onto target stem cells, it can cause skin and respiratory irritation. Aim This study aimed to evaluate the facile fabrication of titanium carbide (Ti3C2)-BiVO4 nanomaterials coupled with oxides for anti-cancer activity. Moreover, it aimed to create Ti3C2-BiVO4 nanomaterials in combination with oxides using X-ray diffraction (XRD) and scanning electron microscopy (SEM) to assess their potential as efficient and targeted anti-cancer agents. Methods and materials To prepare the 2D Ti3C2 MXene, 2.5 g of titanium aluminum carbide (Ti3AlC2) powder was dissolved in 60 mL of a 40% hydrofluoric acid (HF) solution in a polytetrafluoroethylene(PTFE) container. The etching process was made more efficient and completed in 24 hours by using a magnetic stirring system to keep the mixture stirred and heated continuously. The centrifugation was performed at 4000 rpm for five minutes. Subsequently, deionized water was used to wash the solution many times until its pH reached around 7. The appropriate Ti3C2 powder was made by vacuum drying the acquired sediment at 80°C for 24 hours. Monoclinic BiVO4 samples were synthesized via a hydrothermal method. Typically, 10 mmol of Bi(NO3)3.5H2O was dissolved in 100 mL of a 2 mol/L HNO3 solution and stirred uniformly. Subsequently, 10 mmol of ammonium metavanadate (NH4VO3) was added to the mixed solution. After being stirred for one hour, the mixture was transferred into a 100 mL sealed Teflon-lined stainless steel autoclave at 180°C for 16 hours. After cooling to room temperature, the sediment was washed three times with deionized water, ethanol, and acetone, respectively. Finally, the suspension was dried at 80°C, followed by calcination at 450°C for three hours to obtain BiVO4. Ti3C2-BiVO4 heterostructures were prepared by surface modification Ti3C2 using BiVO4 suspensions by a simple, cost-effective approach. Results Ti3C2 nanosheets were observed with BiVO4 particles, and the high crystalline nature of the compound was confirmed after XRD analysis and energy-dispersive spectroscopy (EDS) analysis. The compound was found to be pure without any impurities and exhibited anti-cancer activity. Conclusion The XRD, field emission scanning electron microscopy(FESEM), and EDS investigations provide an in-depth analysis of the structural, morphological, and compositional characteristics of Ti3C2-BiVO4 sheets. The XRD analysis proves the successful combination of different materials and the presence of crystalline phases. The FESEM imaging technique exposes the shape and arrangement of particles in sheets, while the EDS analysis verifies the elemental composition and uniform distribution. These investigations show that Ti3C2-BiVO4 composites have been successfully synthesized, indicating their potential for use in anti-cancer applications.

Facilitated Unidirectional Electron Transmission by Ru Nano Particulars Distribution on MXene Mo2C@g-C3N4 Heterostructures for Enhanced Photocatalytic H2 Evolution

Precious metals exhibit promising potential for the hydrogen evolution reaction (HER), but their limited abundance restricts widespread utilization. Loading precious metal nanoparticles (NPs) on 2D/2D heterojunctions has garnered considerable interest since it saves precious metal consumption and facilitates unidirectional electron transmission from semiconductors to active sites. In this study, Ru NPs loaded on MXenes Mo2C by an in-site simple strategy and then formed 2D/2D heterojunctions with 2D g-C3N4 (CN) via electrostatic self-assembly were used to enhance photocatalytic H2 evolution. Evident from energy band structure analyses such as UV-vis and TRPL, trace amounts of Ru NPs as active sites significantly improve the efficiency of the hydrogen evolution reaction. More interestingly, MXene Mo2C, as substrates for supporting Ru NPs, enriches photoexcited electrons from CN, thereby enhancing the unidirectional electron transmission. As a result, the combination of Ru-Mo2C and CN constructs a composite heterojunction (Ru-Mo2C@CN) that shows an improved H2 production rate at 1776.4 μmol∙g-1∙h-1 (AQE 3.58% at 400 nm), which is facilitated by the unidirectional photogenerated electron transmission from the valence band on CN to the active sites on Ru (CN→Mo2C→Ru). The study offers fresh perspectives on accelerated unidirectional photogenerated electron transmission and saved precious metal usage in photocatalytic systems.

Au/Ti3C2/g-C3N4 Ternary Composites Boost H2 Evolution Efficiently with Remarkable Long-Term Stability by Synergistic Strategies

The use of novel two-dimensional MXene materials and conventional g-C3N4 photocatalysts to fabricate the composites for hydrogen evolution reaction (HER) has attracted much attention, for which there is plenty of room for the enhancement of hydrogen evolution rates particularly under visible light and photostability. Herein, g-C3N4 was modified by copolymerization of malonamide and melamine and used to fabricate the ternary composites of Au particles and Ti3C2 MXene, and based on the synergistic effect, the composites enhanced the hydrogen evolution rates by 2.1, 99.8, and ∞ times compared with the unmodified g-C3N4 under UV, simulated sunlight, and visible light illumination, respectively. Moreover, the composite exhibited a sustained hydrogen evolution capacity in the cycle test for up to 120 h. Theoretical calculations and experimental results indicated that the hot electrons of Au are injected into the modified g-C3N4 and transferred to Ti3C2 simultaneously along with the photogenerated electrons of the modified g-C3N4 and then further transferred to Au, forming a photogenerated electron transfer channel of Au and modified g-C3N4 → Ti3C2 → Au within the composite. Ti3C2 acts as a bridge for fast separation of photogenerated electrons and holes on Au and modified g-C3N4, playing a key role in the enhanced photocatalytic performance. In addition, the visible light absorption ability of Au also positively contributed to the enhancement of visible light photocatalytic performance by providing hot electrons. Therefore, the selection of suitable cocatalysts for the design of composites is a crucial research direction to improve the photocatalytic performance and photostability of photocatalysts.

In situ synthesis of g-C3N4/Ti3C2Tx nano-heterostructures for enhanced photocatalytic H2 generation via water splitting

Herein, we demonstrated the in situ synthesis of g-C3N4/Ti3C2Tx nano-heterostructures for hydrogen generation under UV visible light irradiation. The formation of the g-C3N4/Ti3C2Tx nano-heterostructures was confirmed via powder X-ray diffraction and supported by XPS. The FE-SEM images indicated the formation of layered structures of MXene and g-C3N4. HR-TEM images and SAED patterns confirmed the presence of g-C3N4 together with Ti3C2Tx nanosheets, i.e., the formation of nano-heterostructures of g-C3N4/Ti3C2Tx. The absorption spectra clearly showed the distinct band gaps of g-C3N4 and Ti3C2Tx in the nano-heterostructure. The increase in PL intensity and broadening of the peak with an increase in g-C3N4 indicated the suppression of electron-hole recombination. Furthermore, the nano-heterostructure was used as a photocatalyst for H2 generation from water and methylene blue dye degradation. The highest H2 evolution (1912.25 μmol/0.1 g) with good apparent quantum yield (3.1%) and an efficient degradation of MB were obtained for gCT-0.75, which was much higher compared to that of the pristine materials. The gCT-0.75 nano-heterostructure possessed a high surface area and abundant vacancy defects, facilitating the separation of charge carriers, which was ultimately responsible for this high photocatalytic activity. Additionally, TRPL clearly showed a higher decay time, which supports the enhancement in the photocatalytic activity of the gCT-0.75 nano-heterostructure. The nano-heterostructure with the optimum concentration of g-C3N4 formed a hetero-junction with the linked catalytic system, which facilitated efficient charge carrier separation also responsible for the enhanced photocatalytic activity.

Enhancing Photocatalytic Hydrogen Evolution by Synergistic Benefits of MXene Cocatalysis and Homo-Interface Engineering

Photocatalytic water splitting holds great promise as a sustainable and cost-effectiveness alternative for the production of hydrogen. Nevertheless, the practical implementation of this strategy is hindered by suboptimal visible light utilization and sluggish charge carrier dynamics, leading to low yield. MXene is a promising cocatalyst due to its high conductivity, abundance of active sites, tunable terminal functional groups, and great specific surface area. Homo-interface has perfect lattice matching and uniform composition, which are more conducive to photogenerated carriers' separation and migration. In this study, a novel ternary heterogeneous photocatalyst, a-TiO2 /H-TiO2 /Ti3 C2 MXene (MXTi), is presented using an electrostatic self-assembly method. Compared to commercial P25, pristine anatase, and rutile TiO2 , as-prepared MXTi exhibit exceptional photocatalytic hydrogen evolution performance, achieving a rate of 0.387 mmol h-1 . The significant improvement is attributable to the synergistic effect of homo-interface engineering and Ti3 C2 MXene, which leads to widened light absorption and efficient carrier transportation. The findings highlight the potential of interface engineering and MXene cocatalyst loading as a proactive approach to enhance the performance of photocatalytic water splitting, paving the way for more sustainable and efficient hydrogen production.

Multi-functional MXene quantum dots enhance the quality of perovskite polycrystalline films and charge transport for solar cells

Recently, two-dimensional (2D) transition metal carbides/nitrides (MXenes) find applications in perovskite solar cells (PSCs), due to their high conductivity, tunable electronic structures, and rich surface chemistry, etc. However, the integration of 2D MXenes into PSCs is limited by their large lateral sizes and relatively-small surface volume ratios, and the roles of MXenes in PSCs are still ambiguous. In this paper, zero-dimensional (0D) MXene quantum dots (MQDs) with an average size of 2.7 nm are obtained through clipping step by step combining a chemical etching and a hydrothermal reaction, which display rich terminals (i.e., -F, -OH, -O) and unique optical properties. The 0D MQDs incorporated into SnO₂ electron transport layers (ETLs) of PSCs exhibit multifunction: 1) increasing the electrical conductivity of SnO₂, 2) promoting better alignments of energy band positions at the perovskite/ETL interface, 3) improving the film quality of atop polycrystalline perovskite. Particularly, the MQDs not only tightly bond with the Sn atom for decreasing the defects of SnO₂, but also interact with the Pb²⁺ of perovskite. As a result, the defect density of PSCs is significantly decreased from 5.21 × 10²¹ to 6.4 × 10²⁰ cm^-3, leading to enhanced charge transport and reduced nonradiative recombination. Furthermore, the power conversion efficiency (PCE) of PSCs is substantially improved from 17.44% to 21.63% using the MQDs-SnO₂ hybrid ETL compared with the SnO₂ ETL. Besides, the stability of the MQDs-SnO₂-based PSC is greatly enhanced, with only ～4% degradation of the initial PCE after storage in ambient condition (25 °C, RH: 30-40%) for 1128 h, as compared to that of the reference device with a rapid degradation of ～60% of initial PCE after 460 h. And MQDs-SnO₂-based PSC also presents higher thermal stability than SnO₂-based device with continuous heating for 248 h at 85 °C. The unique MQDs exhibited in this work might also find other exciting applications such as light-emitting diodes, photodetectors, and fluorescent probes.

Facile synthesis of NiAl2O4/g-C3N4 composite for efficient photocatalytic degradation of tetracycline

Designing high-efficiency photocatalysts responsive to visible light is important for the degradation of antibiotics in water. Heterojunction engineering is undoubtedly an effective strategy to improve the photocatalytic performance. In this work, spinel-type metal oxides (NiAl₂O₄, NAO) are synthesized by a simple sol-gel and calcination process. After compounding graphitic carbon nitride (g-C₃N₄), NAO/g-C₃N₄ heterojunction is obtained, which then is used as the photocatalyst for tetracycline hydrochloride (TC). The effects of photocatalyst dosage, the initial concentration of TC, and solution pH on photodegradation performance are systematically studied. The removal rate of TC on NAO/g-C₃N₄ reach up to ∼90% after visible light irradiation for 2 hr and the degradation rate constant is ∼7 times, and ∼32 times higher than that of pure NAO and g-C₃N₄. The significantly improved photocatalytic activity can be attributed to the synergistic effect between well matched energy levels in NAO/g-C₃N₄ heterojunctions, improvement of interfacial charge transfer, and enhancement of visible light absorption. This study provides a way for the synthesis of efficient photocatalysts and an economic strategy for removing antibiotics contamination in water.

Improved Visible-Light Photocatalytic H2 Evolution of G-C3N4 Nanosheets by Constructing Heterojunctions with Nano-Sized Poly(3-Thiophenecarboxylic Acid) and Coordinating Fe(III)

It is highly desirable to enhance the photogenerated charge separation of g-C₃N₄ by constructing efficient heterojunctions, especially with an additional organic constitution for solar-hydrogen conversion. Herein, g-C₃N₄ nanosheets have been modified controllably with nano-sized poly(3-thiophenecarboxylic acid) (PTA) through in situ photopolymerization and then coordinated with Fe(III) via the -COOH groups of modified PTA, forming an interface of tightly contacted nanoheterojunctions between the Fe(III)-coordinated PTA and g-C₃N₄. The resulting ratio-optimized nanoheterojunction displays a ~4.6-fold enhancement of the visible-light photocatalytic H₂ evolution activity compared to bare g-C₃N₄. Based on the surface photovoltage spectra, measurements of the amount of •OH produced, photoluminescence (PL) spectra, photoelectrochemical curves, and single-wavelength photocurrent action spectra, it was confirmed that the improved photoactivity of g-C₃N₄ is attributed to the significantly promoted charge separation by the transfer of high-energy electrons from the lowest unoccupied molecular orbital (LUMO) of g-C₃N₄ to the modified PTA via the formed tight interface, dependent on the hydrogen bond interaction between the -COOH of PTA and the -NH₂ of g-C₃N₄, and the continuous transfer to the coordinated Fe(III) with -OH favorable for connection with Pt as the cocatalyst. This study demonstrates a feasible strategy for solar-light-driven energy production over the large family of g-C₃N₄ heterojunction photocatalysts with exceptional visible-light activities.

In situ reduction of gold nanoparticles-decorated MXenes-based electrochemical sensing platform for KRAS gene detection

In this work, gold nanoparticles@Ti3C2 MXenes nanocomposites with excellent properties were combined with toehold-mediated DNA strand displacement reaction to construct an electrochemical circulating tumor DNA biosensor. The gold nanoparticles were synthesized in situ on the surface of Ti3C2 MXenes as a reducing and stabilizing agent. The good electrical conductivity of the gold nanoparticles@Ti3C2 MXenes composite and the nucleic acid amplification strategy of enzyme-free toehold-mediated DNA strand displacement reaction can be used to efficiently and specifically detect the non-small cell cancer biomarker circulating tumor DNA KRAS gene. The biosensor has a linear detection range of 10 fM −10 nM and a detection limit of 0.38 fM, and also efficiently distinguishes single base mismatched DNA sequences. The biosensor has been successfully used for the sensitive detection of KRAS gene G12D, which has excellent potential for clinical analysis and provides a new idea for the preparation of novel MXenes-based two-dimensional composites and their application in electrochemical DNA biosensors.

ReS2 with unique trion behavior as a co-catalyst for enhanced sunlight hydrogen production

The interfacial catalytic reaction plays a crucial role in determining hydrogen production efficiency of a photocatalyst. In this work, hollow spherical nano-shell composite (g-C₃N₄/CdS/ReS₂) formed by graphitic carbon nitride (g-C₃N₄), cadmium sulfide (CdS), and rhenium disulfide (ReS₂) was prepared for photocatalytic hydrogen production, with ReS₂ introduced as a relatively inexpensive co-catalyst with excellent performance. It was found that two-electron catalytic reaction took place in this photocatalytic system due to the unique trion behavior of ReS₂ co-catalyst, which greatly enhances the rate of photocatalytic hydrogen production. The tightly bound excitons in the ReS₂ co-catalyst could easily capture the photogenerated electrons in the photocatalytic system to form trions, while g-C₃N₄ in the inner shell and CdS in the middle shell provided sufficient electrons for the formation of trions. The active edge sites of ReS₂ also facilitated the generation and desorption of hydrogen, which creates conditions favoring two-electron catalytic reaction. In addition, oxidation and reduction reactions occurred inside and outside of the hollow spherical nano-shell, respectively, which effectively inhibits the recombination of photogenerated carriers. The unique trion behavior of ReS₂ alters the interfacial catalytic reaction compared to the widely used platinum (Pt) co-catalyst in photocatalytic hydrogen production, which provides a new approach for enhancing the activity of photocatalytic systems.

Enhanced Photocatalytic Hydrogen Production of ZnIn2S4 by Using Surface-Engineered Ti3C2Tx MXene as a Cocatalyst

Developing efficient and stable photocatalysts is crucial for photocatalytic hydrogen production. Cocatalyst loading is one of the effective strategies for improving photocatalytic efficiency. Here, Ti₃C₂T_x (T_x = F, OH, O) nanosheets have been adopted as promising cocatalysts for photocatalytic hydrogen production due to their metallic conductivity and unique 2D characterization. In particular, surface functionalized Ti₃C₂(OH)_x and Ti₃C₂O_x cocatalysts were synthesized through the alkalization treatment with NaOH and a mild oxidation treatment of Ti₃C₂F_x, respectively. ZnIn₂S₄/Ti₃C₂T_x composites, which were fabricated by the in-situ growth of ZnIn₂S₄ nanosheets on the Ti₃C₂T_x surface, exhibited the promoted photocatalytic performance, compared with the parent ZnIn₂S₄. The enhanced photocatalytic performance can be further optimized through the surface functionalization of Ti₃C₂F_x. As a result, the optimized ZnIn₂S₄/Ti₃C₂O_x composite with oxygen functionalized Ti₃C₂O_x cocatalyst demonstrated excellent photocatalytic hydrogen evolution activity. The characterizations and density functional theory calculation suggested that O-terminated Ti₃C₂O_x could effectively facilitate the transfer and separation of photogenerated electrons and holes due to the formation of a Schottky junction, with the largest difference in work function between ZnIn₂S₄ and Ti₃C₂O_x. This work paves the way for photocatalytic applications of MXene-based photocatalysts by tuning their surface termination groups.

Facile Synthesis of 2D/2D Ti2C3/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Generation

ZnIn₂S₄, a novel two-dimensional visible light-responsive photocatalyst, has attracted much attention in the photocatalytic evolution of H₂ under visible light irradiation due to its attractive intrinsic photoelectric properties and geometric configuration. However, ZnIn₂S₄ still has severe charge recombination, which results in moderate photocatalytic performance. Herein, we report the successful synthesis of 2D/2D ZnIn₂S₄/Ti₃C₂ nanocomposites by a facile one-step hydrothermal method. The efficiency of the nanocomposites in photocatalytic hydrogen evolution under visible light irradiation was also evaluated for different ratios of Ti₃C₂, and the optimal photocatalytic activity was achieved at 5% Ti₃C₂. Importantly, the activity was significantly higher than that of pure ZnIn₂S₄, ZnIn₂S₄/Pt, and ZnIn₂S₄/graphene. The enhanced photocatalytic activity is mainly due to the close interfacial contact between Ti₃C₂ and ZnIn₂S₄ nanosheets, which amplifies the transport of photogenerated electrons and enhances the separation of photogenerated carriers. This research describes a novel approach for the synthesis of 2D MXenes for photocatalytic hydrogen production and expands the utility of MXene composite materials in the fields of energy storage and conversion.

Interface Engineering in 2D/2D Heterogeneous Photocatalysts

Assembling different 2D nanomaterials into heterostructures with strong interfacial interactions presents a promising approach for novel artificial photocatalytic materials. Chemically implementing the 2D nanomaterials' construction/stacking modes to regulate different interfaces can extend their functionalities and achieve good performance. Herein, based on different fundamental principles and photochemical processes, multiple construction modes (e.g., face-to-face, edge-to-face, interface-to-face, edge-to-edge) are overviewed systematically with emphasis on the relationships between their interfacial characteristics (e.g., point, linear, planar), synthetic strategies (e.g., in situ growth, ex situ assembly), and enhanced applications to achieve precise regulation. Meanwhile, recent efforts for enhancing photocatalytic performances of 2D/2D heterostructures are summarized from the critical factors of enhancing visible light absorption, accelerating charge transfer/separation, and introducing novel active sites. Notably, the crucial roles of surface defects, cocatalysts, and surface modification for photocatalytic performance optimization of 2D/2D heterostructures are also discussed based on the synergistic effect of optimization engineering and heterogeneous interfaces. Finally, perspectives and challenges are proposed to emphasize future opportunities for expanding 2D/2D heterostructures for photocatalysis.

Enhanced photocatalytic decomposition of phenol in wastewater by using La-TiO2 nanocomposite

In this work, La-TiO₂ nanocomposite was synthesized by loading lanthanum onto TiO₂ and used for improving photodegradation of phenol in wastewater. The characterizations of La-TiO₂ demonstrated that the loading of La onto TiO₂ not only increased its adsorption light zone up to 470 nm but also decreased the band gap energy from 3.1 to 2.64 eV. Photoluminescence spectra of La-TiO₂ confirmed the enhancing separation rate between electron and hole, leading to improve photodegradation efficiency of phenol. The removal rate of phenol was influenced by solution pH and alkaline conditions could bring better removal efficiency. In presence of light, the photodegradation efficiency of phenol by TiO₂ was 64.1%, while it increased up to 93.4% by La-TiO₂ photocatalyst. La-TiO₂ nanocomposite was tested for five cycles and it showed only 13.8% dropping in the photodegradation efficiency of phenol. Besides, over 82% of phenol was removed from the wastewater sample by modified TiO₂, demonstrating the potential of La-TiO₂ photocatalyst for water pollution control.

A Targeted Review of Current Progress, Challenges and Future Perspective of g-C3 N4 based Hybrid Photocatalyst Toward Multidimensional Applications

The increasing demand for searching highly efficient and robust technologies in the context of sustainable energy production totally rely onto the cost-effective energy efficient production technologies. Solar power technology in this regard will perceived to be extensively employed in a variety of ways in the future ahead, in terms of the combustion of petroleum-based pollutants, CO₂ reduction, heterogeneous photocatalysis, as well as the formation of unlimited and sustainable hydrogen gas production. Semiconductor-based photocatalysis is regarded as potentially sustainable solution in this context. g-C₃ N₄ is classified as non-metallic semiconductor to overcome this energy demand and enviromental challenges, because of its superior electronic configuration, which has a median band energy of around 2.7 eV, strong photocatalytic stability, and higher light performance. The photocatalytic performance of g-C₃ N₄ is perceived to be inadequate, owing to its small surface area along with high rate of charge recombination. However, various synthetic strategies were applied in order to incorporate g-C₃ N₄ with different guest materials to increase photocatalytic performance. After these fabrication approaches, the photocatalytic activity was enhanced owing to generation of photoinduced electrons and holes, by improving light absorption ability, and boosting surface area, which provides more space for photocatalytic reaction. In this review, various metals, non-metals, metals oxide, sulfides, and ferrites have been integrated with g-C₃ N₄ to form mono, bimetallic, heterojunction, Z-scheme, and S-scheme-based materials for boosting performance. Also, different varieties of g-C₃ N₄ were utilized for different aspects of photocatalytic application i. e., water reduction, water oxidation, CO₂ reduction, and photodegradation of dye pollutants, etc. As a consequence, we have assembled a summary of the latest g-C₃ N₄ based materials, their uses in solar energy adaption, and proper management of the environment. This research will further well explain the detail of the mechanism of all these photocatalytic processes for the next steps, as well as the age number of new insights in order to overcome the current challenges.

A Comprehensive Review on Graphitic Carbon Nitride for Carbon Dioxide Photoreduction

Inspired by natural photosynthesis, harnessing the wide range of natural solar energy and utilizing appropriate semiconductor-based catalysts to convert carbon dioxide into beneficial energy species, for example, CO, CH₄ , HCOOH, and CH₃ COH have been shown to be a sustainable and more environmentally friendly approach. Graphitic carbon nitride (g-C₃ N₄ ) has been regarded as a highly effective photocatalyst for the CO₂ reduction reaction, owing to its cost-effectiveness, high thermal and chemical stability, visible light absorption capability, and low toxicity. However, weaker electrical conductivity, fast recombination rate, smaller visible light absorption window, and reduced surface area make this catalytic material unsuitable for commercial photocatalytic applications. Therefore, certain procedures, including elemental doping, structural modulation, functional group adjustment of g-C₃ N₄ , the addition of metal complex motif, and others, may be used to improve its photocatalytic activity towards effective CO₂ reduction. This review has investigated the scientific community's perspectives on synthetic pathways and material optimization approaches used to increase the selectivity and efficiency of the g-C₃ N₄ -based hybrid structures, as well as their benefits and drawbacks on photocatalytic CO₂ reduction. Finally, the review concludes a comparative discussion and presents a promising picture of the future scope of the improvements.

MXene coupled graphitic carbon nitride nanosheets based plasmonic photocatalysts for removal of pharmaceutical pollutant

The continuous rise in the amount of industrial and pharmaceutical waste in water sources is an alarming concern. Effective strategies should be developed for the treatment of pharmaceutical industrial waste. Hence the alternative renewable source of energy, such as solar energy, should be utilized for a sustainable future. Herein, a series of Au plasmonic nanoparticle decorated ternary photocatalysts comprising graphitic carbon nitride and Ti₃C₂ MXene has been designed to degrade colourless pharmaceutical pollutants, cefixime under visible light irradiation. These photocatalysts were synthesized by varying the amount of Ti₃C₂ MXene, and their catalytic potential was explored. The optimized photocatalyst having 3 wt% Ti₃C₂ MXene achieved 64.69% removal of the pharmaceutical pollutant, cefixime within 105 min of exposure to visible light. The presence of the Au nanoparticles and MXene in the nanocomposite facilitates the excellent charge carrier separation and increased the number of active sites due to the formation of interfacial contact with graphitic carbon nitride nanosheets. Besides, the plasmonic effect of the Au nanoparticles improves the absorption of light causing enhanced photocatalytic performance of the nanocomposite. Based on the obtained results, a plausible mechanism has been formulated to understand the contribution of different components in photocatalytic activity. In addition, the optimized photocatalyst shows excellent activity and can be reused for up to three cycles without any significant loss in its photocatalytic performance. Overall, the current work provides deeper physical insight into the future development of MXene graphitic carbon nitride-based plasmonic ternary photocatalysts.

Signally enhanced piezo-photocatalysis of Bi0.5Na0.5TiO3/MWCNTs composite for degradation of rhodamine B

Recently, the lead-free piezoelectric material Bi_0.5Na_0.5TiO₃ (BNT) has been adopted for piezo-catalysis and synergistic catalysis, such as piezo-photocatalysis. Nonetheless, the catalytic effect of single BNT is too weak to degrade multifarious contaminants. Here, BNT and multi-walled carbon nanotubes (MWCNTs) composite were prepared and the catalytic performance of BNT was prominently boosted by introducing MWCNTs as the electron capturer. Particularly, the degradation rate of Rhodamine B (RhB, a typical contaminant) could reach 90% within 30 min, with a high rate constant of 0.0805 min^-1. The specific degradation pathway of RhB was analyzed. The formation of oxygen vacancies was confirmed by XPS analysis, and the vital role of oxygen vacancies in the separation of photo-generated carriers was elucidated. Meanwhile, the BNT/MWCNTs composites manifested stronger transient current response compared to single BNT under the action of light irradiation and ultrasonic vibration, respectively. According to impedance analysis, the composites exhibited lower carrier transport resistance. Eventually, the mechanism of enhanced piezo-photocatalysis was explained in detail. This study provides an effective route to break the shackle of carrier recombination and speed up the carrier transport in piezo-photocatalytic materials.

Advances in Titanium Carbide (Ti3C2T x ) MXenes and Their Metal-Organic Framework (MOF)-Based Nanotextures for Solar Energy Applications: A Review

Introducing new materials with low cost and superior solar harvesting efficiency requires urgent attention to solve energy and environmental challenges. Titanium carbide (Ti3C2T x ) MXene, a 2D layered material, is a promising solution to solve the issues of existing materials due to their promising conductivity with low cost to function as a cocatalyst/support. On the other hand, metal-organic frameworks (MOFs) are emerging materials due to their high surface area and semiconducting characteristics. Therefore, coupling them would be promising to form composites with higher solar harvesting efficiency. Thus, the main objective of this work to disclose recent development in Ti3C2T x -based MOF nanocomposites for energy conversion applications to produce renewable fuels. MOFs can generate photoinduced electron/hole pairs, followed by transfer of electrons to MXenes through Schottky junctions for photoredox reactions. Currently, the principles, fundamentals, and mechanism of photocatalytic systems with construction of Schottky junctions are critically discussed. Then the basics of MOFs are discussed thoroughly in terms of their physical properties, morphologies, optical properties, and derivatives. The synthesis of Ti3C2T x MXenes and their composites with the formation of surface functionals is systematically illustrated. Next, critical discussions are conducted on design considerations and strategies to engineer the morphology of Ti3C2T x MXenes and MOFs. The interfacial/heterojunction modification strategies of Ti3C2T x MXenes and MOFs are then deeply discussed to understand the roles of both materials. Following that, the applications of MXene-mediated MOF nanotextures in view of CO2 reduction and water splitting for solar fuel production are critically analyzed. Finally, the challenges and a perspective toward the future research of MXene-based MOF composites are disclosed.

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

Photocatalytic water splitting, CO₂ reduction, and pollutant degradation have emerged as promising strategies to remedy the existing environmental and energy crises. However, grafting of expensive and less abundant noble-metal cocatalysts on photocatalyst materials is a mandatory practice to achieve enhanced photocatalytic performance owing to the ability of the cocatalysts to extract electrons efficiently from the photocatalyst and enable rapid/enhanced catalytic reaction. Hence, developing highly efficient, inexpensive, and noble-metal-free cocatalysts composed of earth-abundant elements is considered as a noteworthy step toward considering photocatalysis as a more economical strategy. Recently, MXenes (two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides) have shown huge potential as alternatives for noble-metal cocatalysts. MXenes have several excellent properties, including atomically thin 2D morphology, metallic electrical conductivity, hydrophilic surface, and high specific surface area. In addition, they exhibit Gibbs free energy of intermediate H atom adsorption as close to zero and less than that of a commercial Pt-based cocatalyst, a Fermi level position above the H₂ generation potential, and an excellent ability to capture and activate CO₂ molecules. Therefore, there is a growing interest in MXene-based photocatalyst materials for various photocatalytic events. In this review, we focus on the recent advances in the synthesis of MXenes with 2D and 0D morphologies, the stability of MXenes, and MXene-based photocatalysts for H₂ evolution, CO₂ reduction, and pollutant degradation. The existing challenges and the possible future directions to enhance the photocatalytic performance of MXene-based photocatalysts are also discussed.

Accelerated Photodegradation of Organic Pollutants over BiOBr/Protonated g-C3N4

Interfacial engineering has emerged as an effective strategy to optimize the photocatalytic activity of heterojunctions. Herein, the interface between graphitic carbon nitride (g-C3N4) and BiOBr was readily regulated by a protonation treatment. The synthesized BiOBr/g-C3N4 heterojunctions were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results show that pretreating g-C3N4 in diluted HCl solution led to a partial protonation of g-C3N4, which ensured intimate contact and high dispersion of supported BiOBr without changing the surface area, bulk g-C3N4 structure, or visible light absorption. The abundant BiOBr/g-C3N4 interfaces remarkably improved the separation and transfer of photogenerated carriers, which produced more h+ and O2●− to accelerate the photocatalytic degradation of organic pollutants. The photocatalytic activities of the BiOBr/g-C3N4 heterojunctions were evaluated by the degradation of RhB under visible-light irradiation (λ ≥ 420 nm). The apparent reaction (pseudo-first-order) rate constant of BiOBr supported on partially protonated g-C3N4 (Bpg-C3N4-0.75) is ca. 3-fold higher than that of BiOBr supported on pristine g-C3N4 (Bg-C3N4), verifying interfacial engineering as an effective strategy to optimize the catalytic activity of heterojunctions.

Solid-State Synthesis of ZnO/ZnS Photocatalyst with Efficient Organic Pollutant Degradation Performance

To improve the separation efficiency of photogenerated carriers in ZnS, constructing a ZnS-based heterostructure with ZnO is assessed to be an efficient strategy, and a ZnO/ZnS photocatalyst was prepared by a solid-phase approach, and the structure and morphology were systematically studied. The ZnO/ZnS photocatalyst showed excellent photocatalytic properties on methyl orange, rhodamine B and tetracycline under UV light irradiation, indicating that the photocatalyst exhibited efficient broad-spectrum photocatalytic performance. Compared with ZnS, the degradation rates of ZnO/ZnS photocatalysts for methyl orange, rhodamine B and tetracycline under UV light increased from 21%, 9% and 32% to 96%, 94% and 93%, respectively, higher than the reported ZnO/ZnS composites synthesized by a novel wet chemical route, attributing to the improvement of light absorption ability and the effective separation of carriers. In addition, the influence of the sacrificial agent on the reaction system was investigated, and the synergistic mechanism of ZnO and ZnS in the catalytic process was analyzed according to the fluorescence spectra, photocurrent and first-principles calculation results, and a possible catalytic mechanism was put forward.

Alkyl group-decorated g-C3N4 for enhanced gas-phase CO2 photoreduction

With excellent physical/chemical stability and feasible synthesis, g-C₃N₄ has attracted much attention in the field of photocatalysis. However, its weak photoactivity limits its practical applications. Herein, by easily planting hydrophobic alkyl groups onto g-C₃N₄, the hydrophilicity of g-C₃N₄ can be well regulated and its specific surface area be enlarged simultaneously. Such a modification ensures enhanced CO₂ capture and increased active sites. In addition, the introduction of alkyl groups endows g-C₃N₄ with abundant charge density and efficient separation of photoinduced excitons. All these advantages synergistically contribute to the enhanced photocatalytic CO₂ reduction performance over the optimized catalyst (DCN90), and the total CO₂ conversion is 7.4-fold that of pristine g-C₃N₄ (CN).

MXenes as Emerging Materials: Synthesis, Properties, and Applications

Due to their unique layered microstructure, the presence of various functional groups at the surface, earth abundance, and attractive electrical, optical, and thermal properties, MXenes are considered promising candidates for the solution of energy- and environmental-related problems. It is seen that the energy conversion and storage capacity of MXenes can be enhanced by changing the material dimensions, chemical composition, structure, and surface chemistry. Hence, it is also essential to understand how one can easily improve the structure-property relationship from an applied point of view. In the current review, we reviewed the fabrication, properties, and potential applications of MXenes. In addition, various properties of MXenes such as structural, optical, electrical, thermal, chemical, and mechanical have been discussed. Furthermore, the potential applications of MXenes in the areas of photocatalysis, electrocatalysis, nitrogen fixation, gas sensing, cancer therapy, and supercapacitors have also been outlooked. Based on the reported works, it could easily be observed that the properties and applications of MXenes can be further enhanced by applying various modification and functionalization approaches. This review also emphasizes the recent developments and future perspectives of MXenes-based composite materials, which will greatly help scientists working in the fields of academia and material science.

Efficient Interfacial Charge Transfer Based on 2D/2D Heterojunctions of Fe-C3N4/Ti3C2 for Improving the Photocatalytic Degradation of Antibiotics

Graphitic carbon nitride (g-C₃N₄) has shown to be a promising photocatalyst that, however, suffers from strong charge recombination and poor conductivity, while MXenes have shown to be perfect cocatalysts for the photocatalytic process but show poor stability. In this study, we successfully constructed 2D/2D heterojunctions of Fe-C₃N₄/Ti₃C₂ for the photocatalytic degradation of antibiotics. In this study, multilayer Ti₃C₂ was obtained by etching Ti₃AlC₂, and then Fe-C₃N₄/Ti₃C₂ photocatalyst was prepared by the one-pot microwave method and high-temperature calcination method. The synthesized samples were characterized by XRD, SEM, TEM, XPS, TGA, BET, DRS, PL, and other means. The photocatalytic degradation of tetracycline hydrochloride by Fe-C₃N₄/Ti₃C₂ was in accordance with the first-order reaction kinetics model, and the apparent rate constant k was 2.83, 2.06, and 1.77 times that of g-C₃N₄, Fe-C₃N₄, and g-C₃N₄/Ti₃C₂, respectively. Through the mechanism study, it was shown that the most active species in the reaction system was • O₂⁻, while h⁺ and •OH had a relatively lower effect on the degradation system.

Manganese Cadmium Sulfide Nanoparticles Solid Solution on Cobalt Acid Nickel Nanoflakes: A Robust Photocatalyst for Hydrogen Evolution

Photocatalytic water splitting for hydrogen evolution is one of the most promising methods to mitigate environmental and energy-related issues. In this study, manganese cadmium sulfide (Mn_x Cd_1-x S) solid solution is used to construct a p-n heterostructure with NiCo₂ O₄ through a hydrothermal method. The Mn_0.25 Cd_0.75 S/NiCo₂ O₄ composites are used for photocatalytic hydrogen evolution reaction, and the optimal hydrogen rate with 40 mg of Mn_0.25 Cd_0.75 S/NiCo₂ O₄ 40 mg (MCS/NCO 40) is 61159 μmol g^-1  h^-1 , which is about 16.3 times than that of pure Mn_0.25 Cd_0.75 S. After combining with NiCo₂ O₄ , the light absorption scale, the separation efficiency of photogenerated carriers, and the reaction kinetics are enhanced. Moreover, the band offset of MCS/NCO composites is calculated by the core level alignment method, demonstrating the formation of a p-n heterostructure. The built-in electric field from the p-n heterostructure drives charge transfer and enhances separation efficiency, which results in improved photocatalytic performance.

Fabrication of 2H/3C-SiC heterophase junction nanocages for enhancing photocatalytic CO2 reduction

The morphology and structure of photocatalyst play an important role in photocatalytic activity. SiC semiconductor is considered as a promising material for the photocatalytic CO₂ reduction due to its negative conduction band position. Herein, SiC nanocages is creatively synthesized by simple low-temperature molten-salt-mediated magnesiothermic reduction method with using SiO₂ as template. The morphology and phase composition of SiC nanocages can be controlled by magnesium dosage and reaction temperature. The 2H and 3C crystal phase in SiC nanocage can form heterophase junctions uniformly to effectively accelerate the photogenerated electron transfer, and plays a key role in improving the photocatalytic activity of 2H/3C-SiC samples. The optimal SiC nanocage sample possesses a CO generation rate of 4.68 μmol g^-1h^-1 for photocatalytic CO₂ reduction, which is 3.25 times higher than that of commercial SiC.

COF-5/CoAl-LDH Nanocomposite Heterojunction for Enhanced Visible-Light-Driven CO2 Reduction

Photocatalytic conversion of CO₂ into value-added chemical fuels is an attractive route to mitigate global warming and the energy crisis. Reasonable design of optical properties and electronic behavior of the photocatalyst are essential to improve their catalytic activity. Herein, the 1D/2D heterojunction by direct in-situ synthesis of the covalent organic framework (COF)-5 colloid on the surface of CoAl layered double hydroxide (LDH) was used as the prospective photocatalyst for CO₂ reduction. COF-5/CoAl-LDH nanocomposite achieved 265.4 μmol g^-1 of CO with 94.6 % selectivity over CH₄ evolution in 5 h under visible light irradiation, which was 4.8 and 2.3 times higher than those of COF-5 colloid and CoAl-LDH, respectively. The enhanced catalytic activity was derived from the increased visible-light activity and the construction of type II-2 heterojunction, which greatly optimized visible light harvesting and accelerated the efficient separation of the photoinduced holes and electrons. This work paves the way for rational design of heterojunction catalysts in photocatalytic CO₂ reduction.

MXenes based nano-heterojunctions and composites for advanced photocatalytic environmental detoxification and energy conversion: A review

Extensive research is being done to develop multifunctional advanced new materials for high performance photocatalytic applications in the field of energy production and environmental detoxification, MXenes have emerged as promising materials for enhancing photocatalytic performance owing to their excellent mechanical properties, appropriate Fermi levels, and adjustability of chemical composition. Numerous experimental and theoretical research works implied that the dimensions of MXenes have a significant impact on their performance. For photocatalysis to thrive in the future, we must understand the current state of the art for MXene in different dimensions. Using MXene co-catalysts in widely used in photocatalytic applications such as CO₂ reduction, hydrogen production and organic pollutant oxidation, this study focuses on the most recent developments in MXenes based materials, structural modifications, innovations in reaction and material engineering. It has been reported that using 5 mg of CdS-MoS₂-MXene researchers were able to generate as high as 9679 μmol/g/h hydrogen under visible light. The MXenes based heterojunction photocatalyst Co₃O₄/MXene was utilized to degrade 95% bisphenol A micro-pollutant in just 7 min. Numerous novel materials, their preparations and performances have been discussed. Depending upon the nature of MXene-based materials, the synthesis techniques and photocatalytic mechanism of MXenes as co-catalyst are also summarized. Finally, some final thoughts and prospects for developing highly efficient MXene-based photocatalysts are provided which will indeed motivate researchers to design novel hybrid materials based on MXenes for sustainable solutions to energy and pollution issues.

In situ synthesis of 2D/2D MXene-COF heterostructure anchored with Ag nanoparticles for enhancing Schottky photocatalytic antibacterial efficiency under visible light

It is a major challenge to combine the advantages of two kinds of two-dimensional materials to construct a heterojunction and achieve efficient photocatalytic antifouling. In this work, we covalently connected two materials MXenes and covalent organic frameworks (COFs) through the Schiff base reaction and anchored Ag nanoparticles (NPs) to prepare a Ti₃C₂/TpPa-1/Ag composite material with high efficiency bactericidal properties. The covalent bonding between MXene and COF greatly improved the stability of the material. Ti₃C₂/TpPa-1/Ag composite showed an excellent antibacterial property against S. aureus and P. aeruginosa. The fluorescence spectra of Ti₃C₂/TpPa-1/Ag proved that the electron transfer channels formed between the ternary materials could greatly improve the efficiency of carrier separation and prolong the life of photogenerated carriers. Density functional theory calculations showed that the synergistic catalytic effect of Ag and Ti₃C₂ could greatly reduce the work function along the interface, and the built-in electric field between the layers drive carrier fast migration, which effectively improve the catalytic performance.

Modulation of Water Dissociation Kinetics with a "Breathable" Wooden Electrode for Efficient Hydrogen Evolution

Innovative breakthroughs regarding self-supported open and porous electrodes that can promote gas-liquid transmission and regulate the water dissociation kinetics are critical for sustainable hydrogen economy. Herein, a free-standing porous electrode with Pd-NiS nanoparticles assembled in a multichannel carbonized wood framework (Pd-NiS/CW) was ingeniously constructed. Specifically, carbonized wood (CW) with a mass of open microchannels and high electrical conductivity can significantly facilitate electrolyte permeation ("inhalation"), hydrogen evolution ("exhalation"), and electron transfer. As expected, the fabricated "breathable" wooden electrode exhibits remarkable hydrogen evolution activity in 1.0 M KOH, only requiring a low overpotential of 80 mV to sustain a current density of 10 mA cm^-2, and can maintain this current density for 100 h. Further, the spectroscopic characterization and density functional theory (DFT) calculations manifest that the electron interaction between Pd and NiS is beneficial to reduce the water dissociation energy barriers, optimize the adsorption/desorption of H, and ultimately accelerate the catalytic activity. The work reported here will provide a potential approach for the design of electrocatalysts combined with natural multichannel wood to achieve the goal of high electrocatalytic activity and superior durability for hydrogen production.

Recent Advancement of the Current Aspects of g-C3 N4 for its Photocatalytic Applications in Sustainable Energy System

Being one of the foremost enticing and intriguing innovations, heterogeneous photocatalysis has also been used to effectively gather, transform, and conserve sustainable sun's radiation for the production of efficient and clean fossil energy as well as a wide range of ecological implications. The generation of solar fuel-based water splitting and CO₂ photoreduction is excellent for generating alternative resources and reducing global warming. Developing an inexpensive photocatalyst can effectively split water into hydrogen (H₂ ), oxygen (O₂ ) sources, and carbon dioxide (CO₂ ) into fuel sources, which is a crucial problem in photocatalysis. The metal-free g-C₃ N₄ photocatalyst has a high solar fuel generation potential. This review covers the most recent advancements in g-C₃ N₄ preparation, including innovative design concepts and new synthesis methods, and novel ideas for expanding the light absorption of pure g-C₃ N₄ for photocatalytic application. Similarly, the main issue concerning research and prospects in photocatalysts based g-C₃ N₄ was also discussed. The current dissertation provides an overview of comprehensive understanding of the exploitation of the extraordinary systemic and characteristics, as well as the fabrication processes and uses of g-C₃ N₄ .