Selective hydrogenation of CO₂ to yield CH₄ relies on the appropriate catalysts that can facilitate the cleavage of CO bonds and dissociative adsorption of H₂. Ultrafine Rh nanoparticles loaded on silica nanospheres were used as a class of photocatalysts to significantly improve the selectivity and reaction rate of producing CH₄ from the mixture of CO₂ and H₂ under the illumination of a broadband visible light source. The intense light scattering resonances in the silica nanospheres generate strong electric fields near the silica surface to enhance the light absorption power in the supported ultrafine Rh nanoparticles, promoting the efficiency of hot electron generation in the Rh nanoparticles. The interaction of the hot electrons with the adsorbate species on the Rh nanoparticle surface weakens the C–O bond to facilitate the deoxygenation of CO₂, favoring the production of CH₄ with a unity selectivity at a faster rate in the presence of surface adsorbed hydrogen (H*). The systematic studies on reaction kinetics and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy under different conditions, including various temperatures, illumination powers, and feeding gas compositions, reveal the reaction mechanism responsible for CO₂ methanation and the role of photoillumination.

中文翻译：

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超细Rh纳米颗粒光催化CO2甲烷化机理

_{CO 2}选择性加氢产生CH ₄依赖于能够促进CO键断裂和H ₂解离吸附的适当催化剂。二氧化硅纳米球负载超细Rh纳米粒子作为一类光催化剂，可显着提高宽带可见光源照射下CO ₂和H ₂混合物生产CH ₄的选择性和反应速率。二氧化硅纳米球中强烈的光散射共振在二氧化硅表面附近产生强电场，增强了负载的超细Rh纳米颗粒的光吸收能力，从而提高了Rh纳米颗粒中热电子产生的效率。热电子与Rh纳米粒子表面吸附物质的相互作用削弱了C-O键，有利于CO ₂的脱氧，有利于在表面吸附氢存在的情况下以更快的速率以单一选择性产生CH ₄（H*）。对不同条件（包括不同温度、照明功率和进料气体组成）下的反应动力学和漫反射红外傅里叶变换（DRIFT）光谱的系统研究揭示了CO ₂甲烷化的反应机理和光照明的作用。