Spherical cactus-like composite based on transition metals Ni, Co and Mn with 1D / 2D bonding heterostructure for electrocatalytic overall water splitting

Three dimensional nickel foam carried sea urchin-like copper-cobalt-cerium cathode for enhanced tetracycline wastewater purification in photocatalytic fuel cell

Photocatalytic fuel cells (PFCs) regarded as a potential sustainable technique, have been broadly reported. In this work, the carbon quantum dot-loaded TiO2 photoanode and sea urchin-like CuCoCe ternary metal oxide cathode materials are successfully synthesized and used to construct PFC systems for efficient tetracycline (TC) degradation (45 mg/L) and simultaneous electricity generation. The results demonstrate that the CQDs-modified TiO2 photoanode has improved absorption intensity in both the UV and visible regions, and the photocurrent density at 1.23 V vs RHE reached 1.31 mA cm-2, which is 1.3 times higher than that of the original TiO2 photoanode. The established PFC system achieves the highest removal ratio of 96.9 % for TC in 60 min with a maximum power density of 0.77 mW cm-2. The PFC system can operate efficiently over a wide pH range (3.0-9.0). Furthermore, quenching experiments and ESR spectra show that the main reactive oxygen species in the degradation process are •O2-, 1O2 and •OH. This study provides meaningful way to develop multiple metal oxides as cathode of PFC system for efficient organic pollutant degradation and energy recovery.

Cation-doped sea-urchin-like MnO2 for electrocatalytic overall water splitting

It is necessary to take full account of the activity, selectivity, dynamic performance, economic benefits, and environmental impact of the catalysts in the overall water splitting of electrocatalysis for the reasonable design of electrocatalysts. Designing nanostructures of catalysts and optimizing defect engineering are considered environmentally friendly and cost-effective electrocatalyst synthesis strategies. Herein, we report that metal cations regulate the microstructure of sea-urchin-like MnO2 and act as dopants to cause the lattice expansion of MnO2, resulting in crystal surface defects. The valence unsaturated Mn4+/Mn3+ greatly promotes the electrocatalytic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The optimal Al-MnO2 showed that the overpotential is 390 and 170 mV in the process of catalyzing OER and HER, respectively, at a current density of 10 mA cm-2. It is exciting to note that after 5000 cycles of Al-MnO2 within the kinetic potential range of OER and HER, its performance remained almost unchanged. This work provides a simple, efficient, and environmentally friendly route for the design of efficient integrated water-splitting electrocatalysts.

Recent Advances in Engineering of 2D Materials-Based Heterostructures for Electrochemical Energy Conversion

2D materials, such as graphene, transition metal dichalcogenides, black phosphorus, layered double hydroxides, and MXene, have exhibited broad application prospects in electrochemical energy conversion due to their unique structures and electronic properties. Recently, the engineering of heterostructures based on 2D materials, including 2D/0D, 2D/1D, 2D/2D, and 2D/3D, has shown the potential to produce synergistic and heterointerface effects, overcoming the inherent restrictions of 2D materials and thus elevating the electrocatalytic performance to the next level. In this review, recent studies are systematically summarized on heterostructures based on 2D materials for advanced electrochemical energy conversion, including water splitting, CO2 reduction reaction, N2 reduction reaction, etc. Additionally, preparation methods are introduced and novel properties of various types of heterostructures based on 2D materials are discussed. Furthermore, the reaction principles and intrinsic mechanisms behind the excellent performance of these heterostructures are evaluated. Finally, insights are provided into the challenges and perspectives regarding the future engineering of heterostructures based on 2D materials for further advancements in electrochemical energy conversion.

Ti3 C2 -MXene Partially Derived Hierarchical 1D/2D TiO2 /Ti3 C2 Heterostructure Electrode for High-Performance Capacitive Deionization

Constructing faradaic electrode with superior desalination performance is important for expanding the applications of capacitive deionization (CDI). Herein, a simple one-step alkalized treatment for in situ synthesis of 1D TiO₂ nanowires on the surface of 2D Ti₃ C₂ nanosheets, forming a Ti₃ C₂ -MXene partially derived hierarchical 1D/2D TiO₂ /Ti₃ C₂ heterostructure as the cathode electrode is reported. Cross-linked TiO₂ nanowires on the surface help avoid layer stacking while acting as the protective layer against contact of internal Ti₃ C₂ with dissolved oxygen in water. The inner Ti₃ C₂ MXene nanosheets cross over the TiO₂ nanowires can provide abundant active adsorption sites and short ion/electron diffusion pathways. . Density functional theory calculations demonstrated that Ti₃ C₂ can consecutively inject electrons into TiO₂ , indicating the high electrochemical activity of the TiO₂ /Ti₃ C₂ . Benefiting from the 1D/2D hierarchical structure and synergistic effect of TiO₂ and Ti₃ C₂ , TiO₂ /Ti₃ C₂ heterostructure presents a favorable hybrid CDI performance, with a superior desalination capacity (75.62 mg g^-1 ), fast salt adsorption rate (1.3 mg g^-1 min^-1 ), and satisfactory cycling stability, which is better than that of most published MXene-based electrodes. This study provides a feasible partial derivative strategy for construction of a hierarchical 1D/2D heterostructure to overcome the restrictions of 2D MXene nanosheets in CDI.

Progress on photocatalytic semiconductor hybrids for bacterial inactivation

Due to its use of green and renewable energy and negligible bacterial resistance, photocatalytic bacterial inactivation is to be considered a promising sterilization process. Herein, we explore the relevant mechanisms of the photoinduced process on the active sites of semiconductors with an emphasis on the active sites of semiconductors, the photoexcited electron transfer, ROS-induced toxicity and interactions between semiconductors and bacteria. Pristine semiconductors such as metal oxides (TiO₂ and ZnO) have been widely reported; however, they suffer some drawbacks such as narrow optical response and high photogenerated carrier recombination. Herein, some typical modification strategies will be discussed including noble metal doping, ion doping, hybrid heterojunctions and dye sensitization. Besides, the biosafety and biocompatibility issues of semiconductor materials are also considered for the evaluation of their potential for further biomedical applications. Furthermore, 2D materials have become promising candidates in recent years due to their wide optical response to NIR light, superior antibacterial activity and favorable biocompatibility. Besides, the current research limitations and challenges are illustrated to introduce the appealing directions and design considerations for the future development of photocatalytic semiconductors for antibacterial applications.

Sulfur defect rich Mo-Ni3S2 QDs assisted by O-C[double bond, length as m-dash]O chemical bonding for an efficient electrocatalytic overall water splitting

Developing earth-abundant and highly efficient electrocatalysts is critical for further development of a system. The metal (M) doping strategy and inorganic/organic composite are two common strategies to improve the performance of electrocatalysts for overall water splitting (OWS). In this paper, two strategies are subtly used to prepare Mo-Ni₃S₂ quantum dots (QDs) with rich sulfur defects through Moⁿ⁺ doping Ni₃S₂ and introduction of trisodium citrate by a two-step hydrothermal reaction. Results show that high sulfur defects can be controllably prepared as the lattice mismatch and active sites can be efficiently increased via Moⁿ⁺ doping. Moreover, the introduction of trisodium citrate with carboxyl functional groups not only enhances the degree of sulfur defects around the metal center, changes the morphology of sulfide to distribute the active centers evenly, but also endow the metal center with strong valence changing ability with organic characteristics. The in situ Raman study reveals that O-C[double bond, length as m-dash]O promotes the formation of the real active site M-OOH by the way of self-sacrifice during the OER process. Mo-Ni₃S₂ QDelectrocatalyst shows excellent performance in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), achieving a current density of 10 mA cm^-2 at the overpotentials of 115 mV and 222 mV with very good chemical stability, superior than that of most of the reported materials. The OWS reaction can provide a current density of 10 mA cm^-2 and 50 mA cm^-2, which only needs 1.53 V and 1.74 V with excellent industrial application prospects.

1D/2D Heterostructured Photocatalysts: From Design and Unique Properties to Their Environmental Applications

With the progress of dissimilar dimensional materials, 1D and 2D materials have been extensively investigated as heterogeneous photocatalysts, which realize the unique dimensionality-dependent advantages and mitigate the disadvantages during the environmental and sustainable energy applications. The progress in 1D/2D heterogeneous photocatalysts stems from the combination of different growth modes between 1D and 2D nanostructures and the judicious control to establish the oriented 1D/2D interface. To promote this field, it is necessary to gain insights into the interface engineering in the 1D/2D heterogeneous photocatalysts. This mini-review summarizes the designed synthesis and application of dimensional heterogeneous photocatalysts from 1D and 2D materials. Some typical research to overview the advantages of different types of interface engineered 1D/2D heterogeneous photocatalysts for various photocatalytic processes is highlighted in detail. At last, this review ends by drawing on more design strategies for such 1D/2D heterogeneous photocatalysts, which may inspire further developments of efficient dissimilar dimensional heterogeneous photocatalysts.

Adjustable anchoring of Ni/Co cations by oxygen-containing functional groups on functionalized graphite paper and accelerated mass/electron transfer for overall water splitting

NCS–NCO/FGP_0.44 with a cellular network of porous nanosheets and close-contact heterointerface reveals accelerated interfacial mass/electron transportation for overall water splitting.

Optimization of the overall water-splitting performance of N, S co-doped carbon-supported NiCoMnSx−10 at high current densities by the introduction of sulfur defects and oxygen vacancies

This work reports the synthesis of N and S co-doped carbon-supported NiCoMnS_x−10 electrocatalyst and its application in electrocatalytic overall water splitting.