Copper-tin composite bimetallic nanoparticles on bismuth vanadate nanoplate photocathodes for photoelectrochemical carbon dioxide reduction

Photoelectrochemically (PEC) CO 2 reduction reaction (CO 2 RR) has emerged as one of the most promising methods to mitigate environmental issues. Among metal-based catalysts, copper-tin (CuSn) composite nanoparticles (NPs) have been widely reported for electrochemically reducing CO 2 RR and producing formic acid but have rarely been studied for PEC CO 2 RR. Herein, we chose the nontoxic and low-cost bismuth vanadate (BiVO 4 ) nanoplates as the light-absorbing substrate and applied CuSn NPs on BiVO 4 (CuSn NPs@BiVO 4 ) to form type-II heterojunctions. Under the negative applied voltage, electrons transport through band bending of BiVO 4 via the tunneling and hopping effect and have a reduction reaction on the sample surface. The as-fabricated photocathodes show the highest photoresponse current of −0.774 mA cm −2 at the applied voltage of −0.95 V vs. E Ag/AgCl (−0.33 V vs. RHE) which is 3 times higher than the pristine BiVO 4 photocathodes. This work demonstrated the potential of Cu-Sn bimetallic NPs and BiVO 4 nanoplates for the high-performance PEC CO 2 RR. • Copper-tin composite nanoparticles loaded on BiVO 4 nanoplate films were synthesized as photocathodes. • CuSn NPs@BiVO 4 was prepared for photoelectrochemically CO 2 reduction reaction. • Type-II heterojunctions were formed between BiVO 4 and CuSn NPs.