Construction of Full Solar-Spectrum-Driven Cu_2–xS/Ni-Al-LDH Heterostructures for Efficient Photocatalytic CO₂ Reduction

The reduction of CO2 to hydrocarbons through photocatalysis is a promising way to realize “carbon-neutral”. Nevertheless, developing efficient photocatalysts to achieve high solar energy conversion efficiency and CO2 conversion efficiency is a challenge. Here, we constructed a defective Cu2–xS/Ni-Al-LDH heterojunction photocatalyst via a hydrothermal method. The designed Cu vacancies in Cu2–xS and multiband transition of layered double hydroxide (LDH) promised its efficient solar energy utilization, showing decent CO2 photoreduction performance in both the full-spectrum and near-infrared (NIR) regions. The optimized 15% Cu2–xS/LDH composite achieved CH4 and CO yields of 14.2 μmol/g/h (2.83 μmol/g/h in the NIR region) and 5.3 μmol/g/h (2.99 μmol/g/h in the NIR region), respectively. Furthermore, the corresponding apparent quantum efficiency (AQE) of a 15% Cu2–xS/LDH catalyst is 3.86% at 420 nm. Experimental and characterization results suggested that the enhanced CO2 photoreduction performance could be ascribed to the fabricated p–n heterojunction with a Z-scheme charge transfer route between Cu2–xS and LDH, which inhibited the electron–hole recombination and improved the reaction kinetic energy owing to a higher conduction potential. The fabricated binary catalytic system with the nonprecious metal Cu2–xS and LDH has great prospects for realizing cost-efficient CO2 photoreduction.