Diesel engine has attracted much attention because of its good power performance, fuel economy, reliability and durability, but the exhaust gas containing soot has a great impact on the environment and human health. Catalyzed diesel particulate filter (CDPF) that reduces the activation energy of soot oxidation and combustion by catalysts are used to eliminate soot. In this paper, MFe2O4 spinel (M=Cu, Ni and Co) was synthesized by sol-gel method to catalyze the combustion of soot. The Characterization results of MFe2O4 showed that CuFe2O4 possessed the smallest average grain size (65.6nm) and the best redox performance. The activity test of the catalyst shows that the activity order of the catalyst is CuFe2O4 (330 °C > CoFe2O4 (411 °C > NiFe2O4 (464 °C). DFT results showed that carbon is more easily adsorbed on the oxygen-terminal surface of CuFe2O4 and reacts with oxygen vacancies, resulting in the promotion of soot oxidation by the diffusion of oxygen from the inside to the surface. It also proves that CuFe2O4 has the best catalytic effect on soot.
Solar-driven steam generation as a potential green technology has attracted extensive attention to solve the freshwater scarcity crisis. Photothermal materials as the key section of solar steam generation have been widely reported. However, there is still a challenge in developing easily prepared, environmental-friendly, and low-cost materials. Herein, the simple, scalable, and porous carbonized cotton was prepared as an evaporator to enhance solar-based evaporation, which has excellent light absorption ability in the range of the full spectrum (300–2,500 nm). Benefiting from 95% solar absorption and the pores between the cellulose tubes, the carbonized cotton heated by plate carbonization reaches a steam generation rate of 0.8 kg m−2 h−1, which is about 5 times that of untreated cotton. Compared with tube furnace carbonization, flat plate heating carbonization of cotton requires lower equipment requirements and does not need nitrogen protection and cleaning tar, and the photothermal conversion efficiencies of both are similar. In addition, carbonized cotton as an evaporator was heated up rapidly under 1 sun irradiation and reached a stable temperature in 20 s, greatly improving the photothermal conversion rate. Therefore, plate heating carbonized cotton provides a good idea for preparing solar photothermal conversion materials and a novel strategy for simplifying the production of biomass thermal evaporators.
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