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Solar water splitting over Rh <sub/>0.5</sub> Cr <sub/>1.5</sub> O <sub/>3</sub> -loaded AgTaO <sub/>3</sub> of a valence-band-controlled metal oxide photocatalyst
摘要： Improvement of water splitting performance of AgTaO3 (BG 3.4 eV) of a valence-band-controlled photocatalyst was examined. Survey of cocatalysts revealed that a Rh0.5Cr1.5O3 cocatalyst was much more effective than Cr2O3, RuO2, NiO and Pt for water splitting into H2 and O2 in a stoichiometric amount. The optimum loading amount of the Rh0.5Cr1.5O3 cocatalyst was 0.2 wt%. The apparent quantum yield (AQY) at 340 nm of the optimized Rh0.5Cr1.5O3(0.2 wt%)/AgTaO3 photocatalyst reached to about 40%. Rh0.5Cr1.5O3(0.2 wt%)/AgTaO3 gave a solar to hydrogen conversion efficiency (STH) of 0.13% for photocatalytic water splitting under simulated sunlight irradiation. Bubbles of gasses evolved by the solar water splitting were visually observed under atmospheric pressure at room temperature.
关键词： Rh0.5Cr1.5O3 cocatalyst,valence-band-controlled photocatalyst,solar water splitting,apparent quantum yield,AgTaO3,solar to hydrogen conversion efficiency
更新于2025-11-19 16:51:07
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Unraveling the impact of the Pd nanoparticle@BiVO <sub/>4</sub> /S-CN heterostructure on the photo-physical & opto-electronic properties for enhanced catalytic activity in water splitting and one-pot three-step tandem reaction
摘要： Pd nanoparticles embedded SBVCN-37 heterostructure photocatalyst is synthesized and employed in the water splitting reaction and for the synthesis of imines via one-pot tandem reaction involving photocatalytic reduction of nitrobenzene, oxidation of benzyl alcohol, followed by condensation reaction between them. Embedded Pd nanoparticles (mean diameter ~ 5-7 nm) act as an electron mediator and enhance the catalytic activity during oxidation and reduction reactions. Experimental results confirm that the light induced holes owing to its favourable redox potential oxidize N2H4 to N2 and liberate H+ ions that subsequently react with photogenerated electrons and facilitate the nitrobenzene reduction. The obtained quantum yield for benzyl alcohol oxidation and nitrobenzene reduction are calculated to be (2.08 %) and (6.53 %) at λ = 420 nm light illumination. The obtained apparent quantum yields for OER and HER are calculated to be 10.22 % and 12.72 % at 420 nm indicating the excellent potentiality of the presently investigated photocatalyst for solar fuel production. Photoelectrochemical (PEC) and time resolved & steady state photoluminescence measurements reveal that an optimum amount of Pd nanoparticles over SBVCN-37 is the crucial factor for achieving the highest photocurrent response, the lowest charge transfer resistance, and the efficient carrier’s mobility alteration leading to a prominent catalytic activity. Further, Mott-Schottky (M-S) analysis confirms that the deposition of Pd nanoparticles effectively reduces the over-potential and fine-tunes the band edge potential required for HER and OER reactions, independently.
关键词： Tandem Reaction,BiVO4,Benzyl Alcohol Oxidation,Apparent Quantum Yield,Nitrobenzene Reduction,g-C3N4,Photocatalytic H2 and O2 Production
更新于2025-09-19 17:15:36
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Extending the ?-electron conjugation in 2D planar graphitic carbon nitride: Efficient charge separation for overall water splitting
摘要： We report the direct overall pure water splitting by visible light excited graphitic carbon nitride incorporated with conjugated aromatic rings without using sacrificial agents. We fabricated the modified graphitic carbon nitride polymer samples by copolymerization of melamine with 2,4,6-triaminopyrimidine and 1,3,5-triaminobenzene, containing a few-carbon (pyrimidine) to all-carbon (benzene) aromatic rings. Solid state 13C NMR shows that the core molecular skeleton of g-C3N4 remained intact even after the incorporation of benzene and pyrimidine aromatic rings into g-C3N4 chemical structure. Upon substitution of benzene aromatic ring in the place of triazine ring, the optical band gap energy of g-C3N4 is narrowed down from 2.8 eV to 2.1 eV with negative shifts of valence and conduction bands and due to the formation of defects like nitrogen vacancies. The DFT calculations predict that the benzene doped carbon nitride polymer has localized charge densities over valence band maxima and conduction band minima in different parts of heptazine rings, which assist in reducing the recombination rate of the charge carriers. The benzene ring incorporated carbon nitride photoelectrode shows higher photocurrent with lesser charge transfer resistance than the parent g-C3N4 and pyrimidine doped g-C3N4 polymers. This demonstrates the importance of the extended conjugation in g-C3N4 due to the presence of aromatic benzene rings. This is further corroborated by photoluminescence and electron paramagnetic resonance measurements. As a result, the benzene ring incorporated carbon nitride is more active than the pyrimidine ring incorporated carbon nitride for solar water splitting. The benzene ring incorporated carbon nitride polymer directly splits water and generates about 7 μmol h-1 of hydrogen with apparent quantum yield of 1.6% at 450 nm in the absence of sacrificial reagents, achieving turnover number of 1.6.
关键词： turnover number,benzene,DFT calculations,Carbon nitride,apparent quantum yield,charge separation,pyrimidine,water splitting
更新于2025-09-19 17:15:36