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.