Fig. 2: Design and operation of bias-free driven IAPEC system.

a The transient average photocurrent density diagram of traditional PEC and IAPEC under 100 mW cm⁻² intensity with different cation aqueous solutions. b the theoretical calculation of the Gibbs free energy change for the intermediate species involved in the HER process, as well as the PBAs structure during the insertion process of Na⁺, K⁺ NH₄⁺ and H⁺ ions. The insets depict the corresponding structures and the proposed reaction mechanisms, along with their respective energy level diagrams. c Schematic diagram of the transport process of photogenerated electrons includes a ladder mode representing the bias-driven traditional PEC and a slide mode representing the bias-free drive of the IAPEC system. Error bars representing the standard deviation of three replicate measurements.