太阳能利用和CO2减排是国家重大战略需求。光催化CO2还原制燃料为该需求提供了很有前景的解决方法，但存在光催化原理上很难解决的太阳能至化学能转化效率（η）和燃料生成速率（r）低的巨大挑战。本项目将发展聚焦太阳光驱动CH4还原CO2（CRM）新方法，突破上述挑战。但CRM是强吸热反应，只能在高温下进行，存在热力学上不可避免的积碳副反应，导致催化剂易失活的难题。本项目提出用(SiO2)n、(Al2O3)n团簇对介孔SiO2或Al2O3限域的Ni、Co、Fe纳米晶进行表面相互作用，改变其表面电子状态和几何结构，从动力学上抑制积碳副反应的进行，使其具有优良的稳定性；同时利用这些催化剂的光致热催化新机制、光活化新效应及团簇表面相互作用导致的催化活性增强新效应，显著提高η和r，实现高效聚焦太阳光驱动CRM。将为高效太阳能至化学能转化、CO2减排提供新方法，为CRM提供催化性能优良的纳米结构催化新材料。

The utilization of solar energy and the emission reduction of CO2 are national important strategic needs. Photocatalytic CO2 reduction to produce fuels provides a promising approach for solving the needs. However, there are two great challenges such as low solar-to-chemical efficiency (η) and fuel production rate (r) for the approach, which are very difficultly addressed in photocatalytic principle. In this project, we will develop focused solar light-driven CO2 reduction by methane (CRM) in order to overleap the challenges. However, the CRM reaction is able to proceed only at high temperature due to its highly endothermic property. Thus, there is a problem of catalyst deactivation due to the side reaction of carbon deposit, which is thermodynamically inevitable. In this project, we propose to kinetically prevent the side reaction of carbon deposition through altering the surface electronic state and geometric structure of mesoporous silica or alumina confined Ni, Co or Fe nanocrystals by the surface interaction between the metal nanocrystals and clusters of (SiO2)n or (Al2O3)n, thus making the as-prepared catalysts having excellent catalytic durability. Meanwhile, the focused solar light-driven CRM with high efficiency will be realized by utilizing the novel light-induced thermocatalytic mechanism, novel photoactivation effect, and novel catalytic enhancement effect induced by the interaction between the metal nanocrystals and clusters in the catalysts. The η and r values will be significantly enhanced. The present proposal will provide a novel approach for highly efficient solar-to-chemical conversion and CO2 emission reduction, and provide novel nanostructured catalytic materials with excellent catalytic performance.