Protonated C3N4 Nanosheets for Enhanced Energy Storage in Symmetric Supercapacitors through Hydrochloric Acid Treatment

Next-generation electrochemical energy storage materials are essential in delivering high power for long periods of time. Double-layer carbonaceous materials provide high power density with low energy density due to surface-controlled adsorption. This limitation can be overcome by developing a low-cost, more abundant material that delivers high energy and power density. Herein, we develop layered C3N4 as a sustainable charge storage material for supercapacitor applications. It was thermally polymerized using urea and then protonated with various acids to enhance its charge storage contribution by activating more reaction sites through the exfoliation of the C-N framework. The increased electron-rich nitrogen moieties in the C-N framework material lead to better electrolytic ion impregnation into the electrode, resulting in a 7-fold increase in charge storage compared to the pristine material and other acids. It was found that C3N4 treated with hydrochloric acid showed a very high capacitance of 761 F g-1 at a current density of 20 A g-1 and maintained 100% cyclic retention over 10,000 cycles in a three-electrode configuration, outperforming both the pristine material and other acids. A symmetric device was fabricated using a KOH/LiI gel-based electrolyte, exhibiting a maximum specific capacitance of 175 F g-1 at a current density of 1 A g-1. Additionally, the device showed remarkable power and energy density, reaching 600 W kg-1 and 35 Wh kg-1, with an exceptional cyclic stability of 60% even after 5000 cycles. This study provides an archetype to understand the underlying mechanism of acid protonation and paves the way to a metal-carbon-free environment.

Dual Shield: Bifurcated Coating Analysis of Multilayered WO3/BiVO4/TiO2/NiOOH Photoanodes for Sustainable Solar-to-Hydrogen Generation from Challenging Waters

The heterostructure WO3/BiVO4-based photoanodes have garnered significant interest for photoelectrochemical (PEC) solar-driven water splitting to produce hydrogen. However, challenges such as inadequate charge separation and photocorrosion significantly hinder their performance, limiting overall solar-to-hydrogen conversion efficiency. The incorporation of cocatalysts has shown promise in improving charge separation at the photoanode, yet mitigating photocorrosion remains a formidable challenge. Amorphous metal oxide-based passivation layers offer a potential solution to safeguard semiconductor catalysts. We examine the structural, surface morphological, and optical properties of two-step-integrated sputter and spray-coated TiO2 thin films and their integration onto WO3/BiVO4, both with and without NiOOH cocatalyst deposition. The J-V experiments reveal that the NiOOH cocatalyst enhances the photocurrent density of the WO3/BiVO4 photoanode in water splitting reactions from 2.81 to 3.87 mA/cm2. However, during prolonged operation, the photocurrent density degrades by 52%. In contrast, integrated sputter and spray-coated TiO2 passivation layer-coated WO3/BiVO4/NiOOH samples demonstrate a ∼88% enhancement in photocurrent density (5.3 mA/cm2) with minimal degradation, emphasizing the importance of a strategic coating protocol to sustain photocurrent generation. We further explore the feasibility of using natural mine wastewater as an electrolyte feedstock in PEC generation. Two-compartment PEC cells, utilizing both fresh water and metal mine wastewater feedstocks exhibit 66.6 and 74.2 μmol/h cm2 hydrogen generation, respectively. Intriguingly, the recovery of zinc (Zn2+) heavy metals on the cathode surface in the mine wastewater electrolyte is confirmed through surface morphology and elemental analysis. This work underscores the significance of passivation layer and cocatalyst coating methodologies in a sequential order to enhance charge separation and protect the photoanode from photocorrosion, contributing to sustainable hydrogen generation. Additionally, it suggests the potential of utilizing wastewater in electrolyzers as an alternative to freshwater resources.

MXene-Embedded Porous Carbon-Based Cu2O Nanocomposites for Non-Enzymatic Glucose Sensors

This work explores the use of MXene-embedded porous carbon-based Cu2O nanocomposite (Cu2O/M/AC) as a sensing material for the electrochemical sensing of glucose. The composite was prepared using the coprecipitation method and further analyzed for its morphological and structural characteristics. The highly porous scaffold of activated (porous) carbon facilitated the incorporation of MXene and copper oxide inside the pores and also acted as a medium for charge transfer. In the Cu2O/M/AC composite, MXene and Cu2O influence the sensing parameters, which were confirmed using electrochemical techniques such as cyclic voltammetry, electrochemical impedance spectroscopy, and amperometric analysis. The prepared composite shows two sets of linear ranges for glucose with a limit of detection (LOD) of 1.96 μM. The linear range was found to be 0.004 to 13.3 mM and 15.3 to 28.4 mM, with sensitivity values of 430.3 and 240.5 μA mM-1 cm-2, respectively. These materials suggest that the prepared Cu2O/M/AC nanocomposite can be utilized as a sensing material for non-enzymatic glucose sensors.

Experimental and computational DFT, drift-diffusion studies of cobalt-based hybrid perovskite crystals as absorbers in perovskite solar cells

The optimised designs of dimethyl ammonium cobalt formate-based perovskite crystals [(CH3)2NH2]Co(HCOO)3 were experimentally synthesized and computationally utilized as absorbers for perovskite solar cells (PSCs). Crystals were grown using solvothermal synthesis. Additive materials (Fe, Ni) are responsible for the growth and suppression of crystals in the micrometre range. Temperature and pressure were altered to obtain optimum growth conditions. Grown crystals were characterized by spectroscopy (XRD, FT-IR, UV-Vis) and optical microscopy. Combined density functional theory (DFT) and drift-diffusion modelling frameworks were simulated. These simulators were used to examine various perovskite absorbers for solar-cell configurations. Field calculations were used to examine the structural stability, band structure, and electronic contribution of the constituent elements in [(CH3)2NH2]Co1-nMn(HCOO)3 (M = Fe, Ni and n = 0, 0.1) as absorber material. Conventional TiO2 and spiro-OMeTAD were used as the electron-transport layer and hole-transport layer, respectively, and Pt was used as a back contact. Comprehensive analysis of the effects of several parameters (layer thickness, series and shunt resistances, temperature, generation-recombination rates, current-voltage density, quantum efficiency) was carried out using simulation. Our proposed strategy may pave the way for further design of new absorber materials for PSCs.

Photoelectrocatalytic Surfactant Pollutant Degradation and Simultaneous Green Hydrogen Generation

For the first time, we demonstrate a photoelectrocatalysis technique for simultaneous surfactant pollutant degradation and green hydrogen generation using mesoporous WO3/BiVO4 photoanode under simulated sunlight irradiation. The materials properties such as morphology, crystallite structure, chemical environment, optical absorbance, and bandgap energy of the WO3/BiVO4 films are examined and discussed. We have tested the anionic type (sodium 2-naphthalenesulfonate (S2NS)) and cationic type surfactants (benzyl alkyl dimethylammonium compounds (BAC-C12)) as model pollutants. A complete removal of S2NS and BAC-C12 surfactants at 60 and 90 min, respectively, by applying 1.75 V applied potential vs RHE to the circuit, under 1 sun was achieved. An interesting competitive phenomenon for photohole utilization was observed between surfactants and adsorbed water. This led to the formation of H2O2 from water alongside surfactant degradation (anode) and hydrogen evolution (cathode). No byproducts were observed after the direct photohole mediated degradation of surfactants, implying its advantage over other AOPs and biological processes. In the cathode compartment, 82.51 μmol/cm2 and 71.81 μmol/cm2 of hydrogen gas were generated during the BAC-C12 and S2NS surfactant degradation process, respectively, at 1.75 V RHE applied potential.

Biofunctionalized CdS Quantum Dots: A Case Study on Nanomaterial Toxicity in the Photocatalytic Wastewater Treatment Process

The toxic nature of inorganic nanostructured materials as photocatalysts is often not accounted for in traditional wastewater treatment reactions. Particularly, some inorganic nanomaterials employed as photocatalysts may release secondary pollutants in the form of ionic species that leach out due to photocorrosion. In this context, this work is a proof-of-concept study for exploring the environmental toxicity effect of extremely small-sized nanoparticles (<10 nm) like quantum dots (QDs) that are employed as photocatalysts, and in this study, cadmium sulfide (CdS) QDs are chosen. Typically, CdS is an excellent semiconductor with suitable bandgap and band-edge positions that is attractive for applications in solar cells, photocatalysis, and bioimaging. However, the leaching of toxic cadmium (Cd²⁺) metal ions due to the poor photocorrosion stability of CdS is a matter of serious concern. Therefore, in this report, a cost-effective strategy is devised for biofunctionalizing the active surface of CdS QDs by employing tea leaf extract, which is expected to hinder photocorrosion and prevent the leaching of toxic Cd²⁺ ions. The coating of tea leaf moieties (chlorophyll and polyphenol) over the CdS QDs (referred to hereafter as G-CdS QDs) was confirmed through structural, morphological, and chemical analysis. Moreover, the enhanced visible-light absorption and emission intensity of G-CdS QDs in comparison to that of C-CdS QDs synthesized through a conventional chemical synthesis approach confirmed the presence of chlorophyll/polyphenol coating. Interestingly, the polyphenol/chlorophyll molecules formed a heterojunction with CdS QDs and enabled the G-CdS QDs to exhibit enhanced photocatalytic activity in the degradation of methylene blue dye molecules over C-CdS QDs while effectively preventing photocorrosion as confirmed from cyclic photodegradation studies. Furthermore, detailed toxicity studies were conducted by exposing zebrafish embryos to the as-synthesized CdS QDs for 72 h. Surprisingly, the survival rate of the zebrafish embryos exposed to G-CdS QDs was equal to that of the control, indicating a significant reduction in the leaching of Cd²⁺ ions from G-CdS QDs in comparison to C-CdS QDs. The chemical environment of C-CdS and G-CdS before and after the photocatalysis reaction was examined by X-ray photoelectron spectroscopy. These experimental findings prove that biocompatibility and toxicity could be controlled by simply adding tea leaf extract during the synthesis of nanostructured materials, and revisiting green synthesis techniques can be beneficial. Furthermore, repurposing the discarded tea leaves may not only facilitate the control of toxicity of inorganic nanostructured materials but can also help in enhancing global environmental sustainability.

Facile Synthesis of Gram-Scale Mesoporous Ag/TiO2 Photocatalysts for Pharmaceutical Water Pollutant Removal and Green Hydrogen Generation

This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO₂ and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO₂ photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO₂ nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO₂ effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO₂. Alongside paracetamol degradation, Ag/TiO₂ led to the generation of 1729 μmol H₂ g^-1 h^-1. This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)- and nonmetal (nitrogen)-doped TiO₂, which also showed a positive response. Using a combination of ab initio calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO₂ was due to the surface Fermi-level change of TiO₂ and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.

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.

Sulfonic acid/sulfur trioxide (SO3H/SO3) functionalized two-dimensional MoS2 nanosheets for high-performance photocatalysis of organic pollutants

We report the enhanced photocatalytic activity of sulfonic acid/sulfur trioxide (SO3H/SO3) functionalized two-dimensional (2D)-MoS2 (SO3H/SO3-MoS2) nanosheets synthesized using a one-pot hydrothermal method.

Complete decomposition of sulfamethoxazole during an advanced oxidation process in a simple water treatment system

A simple water treatment system consisting of a deep UV light (λ = 222 nm) source, a mesoporous TiO₂/boron-doped diamond (BDD) photocatalyst, and a BDD electrode was prepared and used to decompose sulfamethoxazole (SMX) in an advanced oxidation process. The mesoporous TiO₂/BDD photocatalyst used with the electrochemical treatment promoted SMX decomposition, but the mesoporous TiO₂/BDD photocatalyst alone had a similar ability to decompose SMX as photolysis. Fragments produced through photocatalytic treatment were decomposed during the electrochemical treatment and fragments produced during the electrochemical treatment were decomposed during the photocatalytic treatment, so performing the electrochemical and photocatalytic treatments together effectively decomposed SMX and decrease the total organic carbon concentration to a trace.

Removal and degradation of mixed dye pollutants by integrated adsorption-photocatalysis technique using 2-D MoS2/TiO2 nanocomposite

Two-dimensional (2D) Molybdenum disulfide (MoS₂) has become one of the most exciting areas of research for adsorbents due to its high surface area and abundant active sites. Mainly, 2D MoS₂ show promising removal of textile dye pollutants by adsorption process, but it show high affinity for anionic type of dyes, that limits its performance in mixed dye pollutants treatment. Herein, we demonstrate an integrated approach to remove mixed dye pollutants (anionic and cationic) concurrently by combining adsorption and photocatalysis process. We synthesize MoS₂/TiO₂ nanocomposites for different weight percentages 2.5, 5, 10, 20, 30 and 50 wt% of pre-synthesized flower-like MoS₂ nanoparticle by a two-step hydrothermal method. We demonstrate a new process of two-stage adsorption/photocatalysis using high wt% of MoS₂ (Stage-I) and low wt% of MoS₂ (Stage-II) nanocomposites. The proposed two-stage integrated adsorption and photocatalysis process using 50% and 2.5% of MoS₂ coated TiO₂, respectively showed complete removal of methylene blue dye ∼5 times faster than conventional single-stage (adsorption or photocatalysis) water treatment process. Furthermore, the feasibility of the proposed two-stage method in mixed dye pollutants removal (anionic and cationic) testified, which showed excellent performance even in doubling the dye pollutant concentration. This work brings a deeper insight into understanding the morphology and concentration of 2-D MoS₂ in MoS₂/TiO₂ nanocomposite in tackling mixed dye pollutants and the possibilities of applying in textile dyeing industries wastewater treatment plants.

NH2-MIL-125(Ti) doped CdS/Graphene composite as electro and photo catalyst in basic medium under light irradiation

The development of active electrocatalysts and photocatalysts for hydrogen evolution reaction (HER) and for environmental remediation is a huge challenge. Research is still underway on the development of low-cost catalytic materials with appreciable efficiency for HER. In the present study, a composite of metal organic framework (MOF) with CdS and graphene (NH₂-MIL-125(Ti)/CdS-graphene) composites were developed with different loadings of graphene material via solvothermal technique. Further the electrocatalytic activity of the synthesized catalysts were investigated for HER and photocatalytic degradation of dye. Results show that the synthesized catalyst with a less amount of graphene was more active. HER results showed a less Tafel slope of 70.8 and 61.9 mVdec^-1 with 15.6 mA/cm² and 15.46 mA/cm² current densities under light on and off conditions. Further the dye degradation activity of the synthesized catalysts was tested with Rhodamine B dye and results showed that the catalyst showed excellent activity for low weight loading of graphene with a degradation efficiency of 95 % and followed pseudo first order kinetic model. Overall results showed that the synthesized composites are promising for HER and photocatalytic applications.

Light-driven transformation of biomass into chemicals using photocatalysts - Vistas and challenges

Lignocellulosic biomass has become an important sustainable resource for fuels, chemicals and energy. It is an attractive source for alternative fuels and green chemicals because it is non-edible and widely available in the planet in huge volumes. The use of biomass as starting material to produce fuels and chemicals leads to closed carbon cycle and promotes circular economy. Although there are many thermo-chemical methods such as pyrolysis, liquefaction and gasification close at hand for processing lignocellulosic biomass and transforming the derived compounds into valuable chemicals and fuels, the photocatalytic method is more advantageous as it utilizes light and ambient conditions for reforming the said compounds. Appraisal of recent literature indicates a variety of photocatalytic systems involving different catalysts, reactors and conditions studied for this purpose. This article reviews the recent developments on the photocatalytic oxidation of biomass and its derivatives into value-added chemicals. The nature of the biomass and derived molecules, nature of the photocatalysts, efficiency of the photocatalysts in terms of conversion and selectivity, influence of reaction conditions and light sources, effect of additives and mechanistic pathways are discussed. Importance has been given also to discuss the complementary technologies that could be coupled with photocatalysis for better conversion of biomass and biomass-derived molecules to value-added chemicals. A summary of these aspects, conclusions and future prospects are given in the end.

A review on recent developments in electrochemical hydrogen peroxide synthesis with a critical assessment of perspectives and strategies

Electrochemical hydrogen peroxide synthesis using two-electron oxygen electrochemistry is an intriguing alternative to currently dominating environmentally unfriendly and potentially hazardous anthraquinone process and noble metals catalysed direct synthesis. Electrocatalytic two-electron oxygen reduction reaction (ORR) and water oxidation reaction (WOR) are the source of electrochemical hydrogen peroxide generation. Various electrocatalysts have been used for the same and were characterized using several electroanalytical, chemical, spectroscopic and chromatographic tools. Though there have been a few reviews summarizing the recent developments in this field, none of them have unified the approaches in catalysts' design, criticized the ambiguities and flaws in the methods of evaluation, and emphasized the role of electrolyte engineering. Hence, we dedicated this review to discuss the recent trends in the catalysts' design, performance optimization, evaluation perspectives and their appropriateness and opportunities with electrolyte engineering. In addition, particularized discussions on fundamental oxygen electrochemistry, additional methods for precise screening, and the role of solution chemistry of synthesized hydrogen peroxide are also presented. Thus, this review discloses the state-of-the-art in an unpresented view highlighting the challenges, opportunities, and alternative perspectives.

Highly Porous MIL-100(Fe) for the Hydrogen Evolution Reaction (HER) in Acidic and Basic Media

The present study reports the synthesis of a porous Fe-based MOF named MIL-100(Fe) by a modified hydrothermal method without the HF process. The synthesis gave a high surface area with the specific surface area calculated to be 2551 m² g^-1 and a pore volume of 1.407 cm³ g^-1 with an average pore size of 1.103 nm. The synthesized electrocatalyst having a high surface area is demonstrated as an excellent electrocatalyst for the hydrogen evolution reaction investigated in both acidic and alkaline media. As desired, the electrochemical results showed low Tafel slopes (53.59 and 56.65 mV dec^-1), high exchange current densities (76.44 and 72.75 mA cm^-2), low overpotentials (148.29 and 150.57 mV), and long-term stability in both media, respectively. The high activity is ascribed to the large surface area of the synthesized Fe-based metal-organic framework with porous nature.

Synergetic Effects of Hybrid Carbon Nanostructured Counter Electrodes for Dye-Sensitized Solar Cells: A Review

This article provides an overview of the structural and physicochemical properties of stable carbon-based nanomaterials and their applications as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The research community has long sought to harvest highly efficient third-generation DSSCs by developing carbon-based CEs, which are among the most important components of DSSCs. Since the initial introduction of DSSCs, Pt-based electrodes have been commonly used as CEs owing to their high-electrocatalytic activities, thus, accelerating the redox couple at the electrode/electrolyte interface to complete the circuit. However, Pt-based electrodes have several limitations due to their cost, abundance, complicated facility, and low corrosion resistance in a liquid electrolyte, which further restricts the large-area applications of DSSCs. Although carbon-based nanostructures showed the best potential to replace Pt-CE of DSSC, several new properties and characteristics of carbon-CE have been reported for future enhancements in this field. In this review, we discuss the detailed synthesis, properties, and performances of various carbonaceous materials proposed for DSSC-CE. These nano-carbon materials include carbon nanoparticles, activated carbon, carbon nanofibers, carbon nanotube, two-dimensional graphene, and hybrid carbon material composites. Among the CE materials currently available, carbon-carbon hybridized electrodes show the best performance efficiency (up to 10.05%) with a high fill factor (83%). Indeed, up to 8.23% improvements in cell efficiency may be achieved by a carbon-metal hybrid material under sun condition. This review then provides guidance on how to choose appropriate carbon nanomaterials to improve the performance of CEs used in DSSCs.

Highly Ordered N-Doped Carbon Dots Photosensitizer on Metal-Organic Framework-Decorated ZnO Nanotubes for Improved Photoelectrochemical Water Splitting

In spite of having several advantages such as low cost, high chemical stability, and environmentally safe and benign synthetic as well as operational procedures, the full potential of carbon dots (CDs) is yet to be explored as photosensitizers due to the challenges associated with the fabrication of well-arrayed CDs with many other photocatalytic heterostructures. In the present study, a unique combination of metal-organic framework (MOF)-decorated zinc oxide (ZnO) 1D nanostructures as host and CDs as guest species are explored on account of their potential application in photoelectrochemical (PEC) water splitting performance. The synthetic strategy to incorporate well-defined nitrogen-doped carbon dots (N-CDs) arrays onto a zeolitic imidazolate framework-8 (ZIF-8) anchored on ZnO 1D nanostructures allows a facile unification of different components which subsequently plays a decisive role in improving the material's PEC water splitting performance. Simple extension of such strategies is expected to offer significant advantages for the preparation of CD-based heterostructures for photo(electro)catalytics and other related applications.

Role of MIL-53(Fe)/hydrated–dehydrated MOF catalyst for electrochemical hydrogen evolution reaction (HER) in alkaline medium and photocatalysis

The role of breathing behavior in hydrated and dehydrated forms of MIL-53(Fe) is investigated here.

Solution Plasma Process-Derived Defect-Induced Heterophase Anatase/Brookite TiO2 Nanocrystals for Enhanced Gaseous Photocatalytic Performance

We report a simple room-temperature synthesis route for increasing the reactivity of a TiO₂ photocatalyst using a solution plasma process (SPP). Hydrogen radicals generated from the SPP chamber interact with the TiO₂ photocatalyst feedstock, transforming its crystalline phase and introducing oxygen vacancy defects. In this work, we examined a pure anatase TiO₂ as a model feedstock because of its photocatalytic attributes and well-characterized properties. After the SPP treatment, the pure anatase crystalline phase was transformed to an anatase/brookite heterocrystalline phase with oxygen vacancies. Furthermore, the SPP treatment promoted the absorption of both UV and visible light by TiO₂. As a result, TiO₂ treated by the SPP for 3 h showed a high gaseous photocatalytic performance (91.1%) for acetaldehyde degradation to CO₂ compared with the activity of untreated TiO₂ (51%). The SPP-treated TiO₂ was also more active than nitrogen-doped TiO₂ driven by visible light (66%). The overall photocatalytic performance was related to the SPP treatment time. The SPP technique could be used to enhance the activity of readily available feedstocks with a short processing time. These results demonstrate the potential of this method for modifying narrow-band gap metal oxides, metal sulfides, and polymer composite-based catalyst materials. The modifications of these materials are not limited to photocatalysts and could be used in a wide range of energy and environment-based applications.