Advantageous Interfacial Effects of AgPd/g‐C 3 N 4 for Photocatalytic Hydrogen Evolution: Electronic Structure and H 2 O Dissociation

Integration of plasmonic AgPd alloy nanoparticles with single-layer graphitic carbon nitride as Mott-Schottky junction toward photo-promoted H2 evolution

Plasmonic AgPd alloy nanoparticles (AgPdNPs) decorated on single-layer carbon nitride (AgPdNPs/SLCN) for the designing of the Mott-Schottky junction were constructed with the ultrasonically assisted hydrothermal method and used toward photo evolution H2 from formic acid (FA) at near room temperature (30 °C). The Pd atom contains active sites that are synergistically boosted by the localized surface plasmon resonance (LSPR) effect of Ag atoms, leading to considerably enhanced photocatalytic properties. The photoactive AgPdNPs/SLCN obtained supreme catalytic activity to produce 50 mL of gas (H2 + CO2) with the initial turnover frequency of 224 h-1 under light irradiation. The catalyst showed stable catalytic performance during successive cycles.

Effects of various alcohol sacrificial agents on hydrogen evolution based on CoS2@SCN nanomaterials and its mechanism

Visible light induced photocatalysis converted solar energy to chemical energy in the form of hydrogen. g-C₃N₄ modified by thermal oxidation etching, doped S, and nonprecious metal cocatalyst CoS₂ (CoS₂@SCN) were used for photocatalytic hydrogen production. And then the charge transfer behavior and mechanism of various alcohol sacrificial agents on hydrogen evolution was analyzed by optical characterization, impedance analysis, Mott-Schottky, and photocurrent tests. The relationship between the structure and catalytic performance was also explored using characterization methods. The results showed that CoS₂ significantly improved the light absorption of g-C₃N₄, and carrier migration and separation. And when the sacrificial agent was triethanolamine, the nanocomposite CoS₂@SCN exhibited best catalytic performance with the highest hydrogen activity of 223.6 μmol g^-1 h^-1, the minimum volume in-phase charge transfer resistance with 55.19 Ω and the maximum photocurrent and photocurrent density with 5.5 μA cm^-2 and 0.63 mA cm^-2. The more negatively charged surface of organic alcohols were, the easier they were to react with holes, thus enhanced charge transfer and hydrogen production efficiency. This report provides guidance for the selection of hydrogen producing sacrificial agents and preparation of highly charge-efficient catalysts. And it also provides a theoretical basis for hydrogen production from wastewater and environmental remediation.

Emerging Cocatalysts on g-C3 N4 for Photocatalytic Hydrogen Evolution

Over the past few decades, graphitic carbon nitride (g-C₃ N₄ ) has arisen much attention as a promising candidate for photocatalytic hydrogen evolution reaction (HER) owing to its low cost and visible light response ability. However, the unsatisfied HER performance originated from the strong charge recombination of g-C₃ N₄ severely inhibits the further large-scale application of g-C₃ N₄ . In this case, the utilization of cocatalysts is a novel frontline in the g-C₃ N₄ -based photocatalytic systems due to the positive effects of cocatalysts on supressing charge carrier recombination, reducing the HER overpotential, and improving photocatalytic activity. This review summarizes some recent advances about the high-performance cocatalysts based on g-C₃ N₄ toward HER. Specifically, the functions, design principle, classification, modification strategies of cocatalysts, as well as their intrinsic mechanism for the enhanced photocatalytic HER activity are discussed here. Finally, the pivotal challenges and future developments of cocatalysts in the field of HER are further proposed.

Engineering of g-C3N4-based photocatalysts to enhance hydrogen evolution

The technology of photocatalytic hydrogen production that converts abundant yet intermittent solar energy into an environmentally friendly alternative energy source is an attractive strategy to mitigate the energy crisis and environmental pollution. Graphitic carbon nitride (g-C₃N₄), as a promising photocatalyst, has gradually received focus in the field of artificial photosynthesis due to its appealing optical property, high chemical stability and easy synthesis. However, the limited light absorption and massive recombination of photoinduced carriers have hindered the photocatalytic activity of bare g-C₃N₄. Therefore, from the perspective of theoretical calculations and experiments, many valid approaches have been applied to rationally design the photocatalyst and ameliorate the hydrogen production performance, such as element doping, defect engineering, morphology tuning, and semiconductor coupling. This review summarized the latest progress of g-C₃N₄-based photocatalysts from two perspectives, modification of pristine g-C₃N₄ and interfacial engineering design. It is expected to offer feasible suggestions for the fabrication of low-cost and high-efficiency photocatalysts and the photocatalytic mechanism analyses assisted by calculation in the near future. Finally, the prospects and challenges of this exciting research field are discussed.

Subnano-Sized Pt-Au Alloyed Clusters as Enhanced Cocatalyst for Photocatalytic Hydrogen Evolution

Photocatalytic water splitting for H₂ evolution is regarded as the most promising way to overcome the energy and environmental crisis. Pt clusters as a cocatalyst can efficiently enhance the performance of H₂ generation in most photocatalysts, but the activity is still unsatisfied. By tuning the electronic structures of materials, one can develop catalysts with enhanced activity. Here we synthesize a Pt-Au alloy with subnano size as cocatalyst on TiO₂ nanosheets for photocatalytic H₂ generation that shows an outstanding activity with a H₂ generation rate of 80.1 μmol h^-1 for at least 100 h. The activity is twice than the pure Pt cocatalyst, mainly because the optimized hydrogen adsorption energy on Pt cluster is tuned by Au atoms.