Integration of Quantum Confinement and Alloy Effect to Modulate Electronic Properties of RhW Nanocrystals for Improved Catalytic Performance toward CO2 Hydrogenation.

Abstract

The d-band center and surface negative charge density generally determine the adsorption and activation of CO2, thus serving as important descriptors of the catalytic activity toward CO2 hydrogenation. Herein, we engineered the d-band center and negative charge density of Rh-based catalysts by tuning their dimensions and introducing non-noble metals to form an alloy. During the hydrogenation of CO2 into methanol, the catalytic activity of Rh75W25 nanosheets was 5.9, 4.0, and 1.7 times as high as that of Rh nanoparticles, Rh nanosheets, and Rh73W27 nanoparticles, respectively. Mechanistic studies reveal that the remarkable activity of Rh75W25 nanosheets is owing to the integration of quantum confinement and alloy effect. Specifically, the quantum confinement in one dimension shifts up the d-band center of Rh75W25 nanosheets, strengthening the adsorption of CO2. Moreover, the alloy effect not only promotes the activation of CO2 to form CO2δ- but also enhances the adsorption of intermediates to facilitate further hydrogenation of the intermediates into methanol.