Exploring the photoelectrochemical process through surface states of plasmonic Ag-loaded NiFe-LDH-modified CuWO4 photoanode

Abstract

Optimizing the interfacial action of photoanode for photoelectrochemical (PEC) behavior to facilitate charge transport is essential for enhancing solar-to-fuel efficiency. Herein, a typical CuWO4/NiFe-LDH/Ag photoanode was reported and an alternative pathway for charge transfer in the PEC process through surface states mechanism was elucidated. In particular, the layer double hydroxides (NiFe-LDH) acted as charge-transfer agents to facilitate the transfer of photogenerated carriers; while the surface plasmon resonance (SPR) effect of the Ag provided hot electrons, which increased the carrier concentration and promoted the charge separation. The influence of presence of surface states on the PEC process was systematically illustrated. Experimental results indicated that the optimized CuWO4/NiFe-LDH/Ag photoanode displayed a photocurrent that was more than an order of magnitude larger than that of the pure CuWO4 (increasing from 0.30 mA cm−2 to 1.45 mA cm−2 at 1.23 V vs. RHE), accompanied by favorable electrochemical impedance and stability (maintaining 92.4%). Importantly, increasing the available filled surface states could be beneficial in enhancing the PEC behavior. This work provided additional insights into photoanode charge transport in PEC processes.