Optional construction of Cu2O@Fe2O3@CC architecture as a robust multifunctional photoelectronic catalyst for overall water splitting and CO2 reduction

[Display omitted] •The Cu2O@Fe2O3@CC-500 electrode shows high activity for overall water splitting.•The electrodes can effectively photocatalyze CO2 reduction under visible light irradiation.•The mechanism has been proposed based on the measurement and DFT calculation. Herein, the flexible self-supported Cu2O@Fe2O3@carbon cloth electrode (named as Cu2O@Fe2O3@CC) has been synthesized by a facile and scalable thermal method. This Cu2O@Fe2O3@CC-500 hierarchical assembly needs ultralow overpotential of 296 mV (for oxygen evolution reaction, OER) and 188 mV (for hydrogen evolution reaction, HER) to afford the 10 mA cm−2 current density, and with the Tafel slope of 66 mV dec−1 (for OER) and 59 mV dec−1 (for HER) in alkaline medium (1.0 M KOH), respectively. The assembled water electrolyzer using bifunctional Cu2O@Fe2O3@CC-500 as both anode and cathode exhibited high stability with a cell voltage of only 1.675 V at 10 mA cm−2. More interestingly, this composite also exhibited excellent photocatalytic performance in CO2 reduction. For the Cu2O@Fe2O3@CC-500, the CO yield attained 172.2 µmol·gcatalyst−1·h−1 under visible light irradiation. Based on the measurements and density functional theory (DFT) calculation, an enhanced OER kinetics and a plausible mechanism for CO2 photo-reduction have been proposed. Our study will open a special door to provide multifunctional phtoelectrocatalyst to be widely used in the clean energy field.