Rapid charge extraction via hole transfer layer and interfacial coordination bonds on hematite photoanode for efficient photoelectrochemical water oxidation

Enhancing carrier separation and transport efficiency to achieve efficient water oxidation reaction is an important issue in photoelectrochemical (PEC) water splitting field, and introducing hole transfer layer (HTL) is an effective strategy to improve it. However, the difficulty of charge transfer between HTL and oxygen evolution catalyst (OEC) is a problem unresolved. To ameliorate the situation, we choose CoOOH as HTL and the metal-organic coordination compound constructed by 4,5-Imidazoledicarboxylic acid (IA) and Co/Ni ions as OEC. Using the interfacial coordination bonds as carrier transfer channels, the holes were rapidly extracted from HTL to OEC containing abundant active sites and participate in oxidation reaction. In consequence, the unique design results in a photocurrent density of 2.97 times that of alpha-Fe2O3 at 1.23 VRHE for the IACN/CoOOH/Fe2O3. This study reveals how the advisable design of photoanode promotes interfacial charge transfer and provides a valuable reference for the design of composite photoanode.