Organic ligand nanoarchitectonics for BiVO4 photoanodes surface passivation and cocatalyst grafting
Jingyi Lin, Xin Li, Zhiliang Wang, Runlu Liu, Hui Pan, Yixin Zhao, Lingti Kong, Yao Li, Shenmin Zhu, Lianzhou Wang
Abstract
Bismuth vanadate (BiVO 4 ) is a promising photoanode material for efficient photoelectrochemical (PEC) water splitting, whereas its performance is inhibited by detrimental surface states. To solve the problem, herein, a low-cost organic molecule 1,3,5-benzenetricarboxylic acid (BTC) is selected for surface passivation of BiVO 4 photoanodes (BVOs), which also provides bonding sites for Co 2+ to anchor, resulting in a Co-BTC-BVO photoanode. Owing to its strong coordination with metal ions, BTC not only passivates surface states of BVO, but also provides bonding between BVO and catalytic active sites (Co 2+ ) to form a molecular cocatalyst. Computational study and interfacial charge kinetic investigation reveal that chemical bonding formed at the interface greatly suppresses charge recombination and accelerates charge transfer. The obtained Co-BTC-BVO photoanode exhibits a photocurrent density of 4.82 mA/cm 2 at 1.23 V vs. reversible hydrogen electrode (RHE) and a low onset potential of 0.22 V RHE under AM 1.5 G illumination, which ranks among the best photoanodes coupled with Co-based cocatalysts. This work presents a novel selection of passivation layers and emphasizes the significance of interfacial chemical bonding for the construction of efficient photoanodes.