Alcohol-Introduced PEDOT:PSS and CuSCN Layers Synergistically Construct GaAs-Based Electrodes for Water Splitting

GaAs/PEDOT:PSS exhibits excellent optoelectronic properties and a matched energy band structure, showing great potential for PEC water splitting. However, the insulating PSS causes severe conductivity loss and low charge separation efficiency in the composite. Herein, n-propanol, 1,2-propanediol, and glycerol are used to modify PEDOT:PSS, with their –OH groups forming electrostatic interactions with PSS’s –SO3H to weaken the PEDOT-PSS Coulombic force and promote PSS dissociation. XPS, FTIR, and AFM characterizations confirm that glycerol achieves the optimal PSS dissociation by forming a multi-dentate hydrogen bond network, which also optimizes PEDOT’s conjugated system for enhanced light absorption. GaAs/glycerol@PEDOT:PSS delivers a photocurrent density of 17.8 mA/cm2 at 1.23 V vs RHE (78% higher than GaAs/PEDOT:PSS) with an ABPE of 12.65% at 0.36 V vs RHE. Introducing CuSCN as a hole transport layer further reduces the electrode impedance and forms a stepped energy band with GaAs and PEDOT:PSS for directional hole transport. The resultant GaAs/CuSCN/glycerol@PEDOT:PSS exhibits a photocurrent density of 20.8 mA/cm2 at 1.23 V vs RHE, an ABPE of 13.75%, a high H2 evolution rate of 138.6 μmol/h, and a Faradaic efficiency of 97.74%. This work provides an effective interfacial engineering strategy for the rational design of high-performance GaAs-based PEC electrodes for water splitting.