Strong Internal Electric Field-Driven S-scheme CoAl-LDH/ZrO Heterojunction for Enhanced Photocatalytic CO Reduction: Configuration, Performance, and Mechanism.

The construction of S-scheme heterojunctions with a strong internal electric field (IEF) is critical for enhancing photocatalytic performance. Herein, an S-scheme heterojunction composed of CoAl-LDH and ZrO (denoted as LZ-60) is synthesized via a hydrothermal method. Under simulated solar irradiation, LZ-60 exhibited a CO production rate of 562.545 µmol g h, which is five times higher than pristine CoAl-LDH and 43 times higher than pristine ZrO. X-ray photoelectron spectroscopy (XPS) revealed electron transfer from CoAl-LDH to ZrO upon hybridization, generating an IEF at the interface. This electron transfer and IEF are further verified by density-functional theory (DFT) calculations of work functions. Comparative XPS analysis before and after the photocatalytic reaction confirmed the S-scheme charge transfer mechanism: the binding energies of Co and Al decreased, while Zr increased, indicating electron transfer from ZrO to CoAl-LDH under light. Photoelectrochemical characterizations (PL, EIS) demonstrated enhanced charge separation in the heterojunction. In-situ Fourier transform infrared spectroscopy identified CO* as the dominant intermediate, confirming high CO selectivity. The accelerated charge separation and strengthened redox capability synergistically contribute to the superior CO reduction performance of the S-scheme LZ-60 heterojunction. This work provides a valuable reference for designing efficient CO reduction photocatalysts.