Stepped-band WO3/CuWO4/CuO nanosheet arrays for efficient photoelectrocatalytic phenol degradation

Rational design of photoelectrodes with abundant active sites and efficient interfacial charge transport is vital for improving photoelectrocatalytic performance. In this work, WO 3 -based heterojunction photoelectrodes were fabricated in situ through a hydrothermal, electrodeposition and annealing process and employed for the photoelectrocatalytic degradation of phenol. The deposition time was optimized to regulate the microstructure and interfacial properties. After annealing, a well-defined two-dimensional ternary heterojunction composed of WO 3 , CuWO 4 , and CuO nanosheet arrays was obtained. This nanoarray architecture maximizes the active sites and specific surface area. Furthermore, the ternary interface promotes efficient charge separation via optimized band alignment and strong coupling. Consequently, the optimal photoanode achieves a photocurrent of 0.91 mA cm −2 (1.21 V vs. RHE), outperforming pristine WO 3 and binary WO 3 /CuWO 4 by factors of 5.2 and 2.2, respectively. The corresponding phenol degradation efficiency reached 84.5%, with a kinetic rate constant of 0.935 h −1 . The improved photoelectrocatalytic activity arises from the synergistic effect of the engineered heterointerface, which accelerates carrier transfer and suppresses recombination. Density functional theory calculations further elucidated the electronic band structures, confirming the stepped-band alignment that favors cascade charge transfer. These findings present a promising strategy for engineering durable and high-efficiency heterostructured photoanodes suitable for wastewater remediation.