In Situ Loading of Cu Nanocrystals on CsCuCl 3 for Selective Photoreduction of CO 2 to CH 4 .

Rational design and facile synthesis of efficient environmentally friendly all-inorganic lead-free halide perovskite catalysts are of great significance in photocatalytic CO 2 reduction. Aiming at photogenerated charge carrier separation and CO 2 reaction dynamics, in this paper, a CsCuCl 3 /Cu nanocrystals (NCs) heterojunction catalyst is designed and synthesized via a simple acid-etching solution process by using Cu 2 O as the sacrificed template. Due to the disproportionation reaction of Cu 2 O induced by concentrated hydrochloric acid, Cu NCs can be deposited onto the surface of CsCuCl 3 microcrystals directly and tightly. As revealed by photoelectrochemical analysis, in situ Fourier transform infrared spectra, etc., the Cu NCs contribute a lot to extracting photoelectrons of CsCuCl 3 to improve the charge separation efficiency, regulating the CO 2 adsorption and activation, and also stabilizing the reaction intermediates. Therefore, CsCuCl 3 /Cu heterojunction exhibits a total electron consumption rate of 58.77 µmol g -1 h -1 , which is 2.9-fold of that of single CsCuCl 3 . Moreover, high CH 4 selectivity of up to 92.7% is achieved, which is much higher than that of CsCuCl 3 (50.4%) and most lead-free halide perovskite-based catalysts. This work provides an ingenious but simple strategy to rationally design cocatalysts in situ decorated perovskite catalysts for manipulating both the catalytic activity and the product selectivity.