Controlled Preparation Of Nanoarray-Structured Catalysts For Photothermal Hydrogenation Of Carbon Dioxide

Photocatalytic conversion of CO2 into fuel using solar energy is a very promising way to alleviate global warming and energy shortages.It remains a key challenge to find suitable photocatalysts and build up highly efficient photocatalytic carbon dioxide reduction systems.Previous studies have shown that the light trapping effect of nanoarray structures could enhance the sunlight harvesting efficiency from the planar structure.However,most existing nanoarray-structured catalysts are based on precious metal elements supported on silicon nanoarrays,which suffers from the high cost,poor stability,complicated preparation process,and lack of environmental friendliness.Compared with silicon material,silica and alumina,more common support materials for metal nanoparticles,have outstanding advantages such as low cost,good thermal stability,and strong interaction with metal catalysts.Therefore,this thesis aims to develop non-precious metal-based catalysts on silica and alumina nanoarrays towards highly efficient photocatalytic reduction of carbon dioxide.Specifically,the following studies have been carried out:In the first part,we have developed a general method for preparing silica nanorod arrays on the substrate by solution-liquid-solid process,and realized the seedless growth of silica nanorod array structures on the surface of hydrophilic substrates.We studied the growth process of SiO2 nanorod arrays on the substrate systematically.By controlling the reaction conditions such as growth time and temperature,the structural parameters of the nanorod array can be designed and optimized.This work laid the foundation for the preparation of metal photothermal catalysts supported on the silica array structure.In the second part,we have constructed a metal/silica array-structured catalyst,which can enhance the absorption of sunlight and enhance the photothermal catalytic performance of carbon dioxide reduction.The carbon dioxide conversion rate of this catalyst in photothermal reduction can reach 0.40 mol gCo-1 h-1,which is 8 times and 140 times as high as that of Co@SiO2-sphere and Co-glass,respectively.This work confirmed that the array-structured catalysts have excellent catalytic performance in the photothermal carbon dioxide reduction reaction,and provided a new idea for constructing photothermal catalysts with high-light absorption.In the third part,we have constructed a metal/anodized alumina array-structured photothermal catalyst.The tightly arranged cobalt metal nanoparticles in this catalyst exhibit a strong plasmonic hybridization effect,which makes the catalyst have excellent catalytic performance in the photothermal carbon dioxide reduction reaction.After adjusting the metal loading and channel type,the optimal conversion rate can reach 1.6 mol gCo-1 h-1,which is nearly 14 times as high as the corresponding planar comparison.