The Function Of Cobalt-Based Co-catalysts For Photocatalytic CO₂ Reduction

Carbon dioxide(CO2)is the most important factor of global warming.Many countries reach a consensus to reduce the emissions of CO2.If we could convert CO2 into some useful chemical fuels,and make it for industrialization possibly,then the economy of our society will be growing and the atmosphere will be better.It is considered as the most promising method.But,current poor selectivity and the activity of catalysts become the main problems in photocatalytic reduction.Improving the efficiency of CO2 photoreduction is of big significance in the field of photocatalysis research.Although the main catalyst is considered to be the dominating factor influencing the efficiency of CO2 photoreduction,the modification with cocatalyst on semiconductor catalyst could plays an important role in further improvement.Frequently,noble metals such as Pt?Pd?Au et al.are widely used as cocatalysts for CO2 photoreduction reaction because of their wondeful perforamnce.Nevertheless,there is a obvious factor immensely impeding its use in practial application because of its high price and low reserves.Therefore,it is very meaningful to develop new low-cost,and stable non-noble-metal cocatalysts applied in photocatalytic reduction of CO2.Based on a comprehensive review of the publications and current issues of photocatalytic CO2 reduction,in this thesis,we take the representative new cobalt-based cocatalysts-spinel oxide NiCo2O4 and CuCo2O4 as the research objects,study the effect of different kinds of semiconductor modified by cocatalysts as for performance of photocatalytic CO2 reduction system.The main details of this stutdies are briefly summarized:(1)We synthesized pure NiCo2O4 microspheres through control the dosage of urea and isopropanol adding into the reaction.Detailedly detect and analyze NiCo2O4 nanomaterial feature operated by various characterization methods.Similarly mesoporous CuCo2O4 nanoplates were synthesized through hydrothermal-calcination methods.We try to find different aspects as surface area and pore structure properties for comparation of samples calcined at different temperature.Starting to focus on these materials applied as cocatalyst cooperate with Ru(bpy)32+ as the photosensitizer in photocatalytic reduction of CO2 system.(2)We try to get uniform catalyst CuCo2O4/CdS through wet chemical method and several percents of CuCo2O4 sample was loaded on the semiconductor CdS,marked as 1wt%CuCo2O4/CdS and so on.To examine the cocatalytic function of CuCo2O4,we establish non-noble-metal CuCo2O4/semiconductor CO2 photoreduciton system under mild reaction condition.The results of this reaction system indicated that the cocatalytic efficiency was remarkably enhanced by CuCo2O4 sample for photocatalytic CO2 reduction.Eventually we draw a conclusion that CuCo2O4 sample present wonderful cocatalytic function and structural stablity.The innovations of my work are as follows:(1)Perfectly examined this functional material could applied in photocatalytic CO2 reduction as cocatalyst,when Ru(bpy)32+was used as photosensitizer in homogeneous reaction system.(2)We make CuCo2O4 load on semiconductor CdS to form uniform catalyst,and new noble-metal-free CuCo2O4/CdS photocatalytic CO2 reduction systems were established.The cocatalytic efficiency of this hetergeneous system was obviously enhanced by CUCo2O4 spinel material.