Unlocking H2-free CO2 reduction: A Z-scheme Ni-MOF/WO3-x heterojunction for superior photothermal catalysis

Heterojunction engineering has garnered significant attention in photocatalysis as an effective strategy to address the rapid carrier recombination dynamics in semiconductor photocatalysts. The core challenge in constructing high-performance heterojunction systems lies in establishing optimized interfacial connections to achieve directional charge carrier migration. This study proposed a temperature-regulated band engineering strategy, through precise control of Ni-MOFs growth temperature and integration with WO 3-x possessing exceptional photothermal conversion capacity, to successfully construct an efficient Z-scheme heterojunction system. When the synthesis temperature of the Ni-MOF reached 140 °C, its conduction band negatively shifted to −1.2 eV (vs. NHE), resulting in a well-matched Z-scheme heterojunction with WO 3-x . The optimized 140-Ni-MOF/WO 3-x heterojunction demonstrated remarkable enhancement in charge separation efficiency while preserving strong redox capabilities through the Z-scheme charge transfer pathway. Under mild gas-solid reaction conditions (H 2 O as electron donor), the optimized catalyst exhibited excellent CO 2 reduction performance, achieving a CO production rate of 111.17 μmol·g −1 with 96.92 % selectivity. The temperature-depended modulation strategy for MOF electronic band structure proposed in this study paved the way for constructing efficient MOF-based photocatalysts.