Investigation And Application Of Weak Sunlight-driven Photothermal Catalysis

Catalytic reaction plays an irreplaceable role in the chemical industry.In human activities,about 90%of the chemical production process is related to catalytic process.However,catalytic reactions consume a lot of fossil fuels and secondary energy,which is one of the key questions of catalytic reactions.Using solar energy to drive catalytic reactions is the most feasible and economical solution to the alleviate energy demand.In recent years,a variety of some solar-driven catalytic processes such as photo,photoelectro or plasmonic,and photothermal catalysis have been developed.Among them,photothermal catalysis is a new research topic.However,due to the low density of the natural sunlight,the temperature of catalysts is too low to drive the catalytic reactions under the irradiation of natural sunlight.The new photothermal device developed by our research group can effectively improve the utilization rate of weak light and thus increase the temperature of the catalyst under weak light irradiation.Based on this,we have developed a photothermal catalysis which combines high efficiency catalyst with new photothermal device for weak optical drive,and explored the application of the new photothermal system in the field of environment and energy?In the paper the main research contents and conclusions are as follows:1.A new photothermal conversion system is proposed that using the principle of selective light absorption and vacuum effect to block the heat radiation of catalysts,reduce the heat conduction and full absorb sunlight simultaneously,so that the solar energy can be efficiently converted as heat energy,and the heat energy is confined in the photothermal device,generating a high temperature to heat the catalyst to more than 285°C under one standard solar light irradiation and finally realizing the catalytic reactions under weak sunlight irradiation without secondary energy input.2.W doped Fe₂O₃ nanosheets were prepared by graphene oxides template method for the thermal and photothermal of the selective catalytic reduction of nitrogen oxides?NO_x SCR?.The W doped Fe₂O₃ nanosheets achieved 88%conversion efficiency,96%N₂ selectivity,and strong resistance for NO_x SCR at 250°C.The W doped Fe₂O₃ nanosheets can be heated to276°C under one standard solar irradiation with the assistance of new photothermal device.As a result,the new photothermal device assisted W doped Fe₂O₃ nanosheets showed 92%and 90%NO conversion rate under one solar irradiation and outdoor sunlight irradiation respectively without second energy input.3.We prepared the CuZnAl catalyst by coprecipitation method for the thermal and photothermal hydrogen production by methanol reforming.The hydrogen production rate of CuZnAl catalyst was 0.4 mol g^-1h^-1 at 260°C.The new photothermal device can heat the CuZnAl catalysts to 299°C under one standard sunlight irradiation.As a result,the combination of new photothermal device and CuZnAl catalysts shows a one standard sunlight-driven hydrogen generation rate of 3033 L m^-2 h^-1,indicating that CuZnAl catalyst can achieve efficient hydrogen production rate from methanol reforming driven by standard sunlight,with the coordination of the new photothermal device.4.We prepared the efficient PVP-CuZnAl catalyst by co-precipitation method with the assistance of buffer and surfactant for the thermal and photothermal of the hydrogen production by methanol reforming.The hydrogen production rate of prepared PVP-CuZnAl catalyst can reach to 1.02 mol g^-1 h^-1 at 260°C.And it is about twice that of commercial CuZnAl catalyst.The new photothermal device can heat the PVP-CuZnAl catalysts to 299°C under one standard sunlight irradiation.As a result,the combination of new photothermal device and CuZnAl catalysts shows a one standard sunlight-driven hydrogen generation rate of 3845 L m^-2 h^-1,corresponding to 878.9 mmol g^-1 h^-1 without any second energy input,which illustrates an industrial scale system on using ambient sunlight to highly efficient produce hydrogen energy.