SnO_(2)/γ-Al_(2)O_(3)粒子电极制备及其电催化还原CO_(2)产甲酸性能研究

Preparation of SnO_(2)/γ-Al_(2)O_(3) Particle Electrode and Its Electrocatalytic Reduction of CO_(2) to Formic Acid

【目的】电催化还原CO_(2)(CO_(2)RR)是降低大气中CO_(2)浓度的绿色可行方案,制备高催化性能和稳定性的催化剂尤为重要。【方法】以γ-Al_(2)O_(3)粒子为载体,采用浸渍-焙烧法制备了SnO_(2)/γ-Al_(2)O_(3)粒子电极用于电催化还原CO_(2)产甲酸来测试其性能,并结合物化分析、电化学测试及长周期实验等手段对粒子电极的微观结构、物相组成、电催化活性、产甲酸性能和稳定性进行了探讨。【结果】物化分析结果表明,负载SnO_(2)前后的形貌由孔洞和裂痕状为主转变为裂层状,比表面积自310.18m^(2)/g增加到352.70m^(2)/g,粒子电极中Sn含量占比48.32%,SnO_(2)成功分散负载到γ-Al_(2)O_(3)表面。据电化学测试所得,SnO_(2)/γ-Al_(2)O_(3)粒子电极的伏安电量(扫速50mV/s)、交换电流密度和析氢电阻分别为40mC、20.02μA/cm^(2)和96.86Ω,与γ-Al_(2)O_(3)相比分别提高了37.93%、75.46%和6.80%,大幅提升CO_(2)RR活性的同时有效抑制了析氢副反应。SnO_(2)/γ-Al_(2)O_(3)粒子电极表现出良好的CO_(2)RR特性,反应时间2h的产甲酸速率为70.35μmol·h-1·cm-2,电流密度为4.94mA/cm^(2),法拉第效率和能量效率分别为79.05%、24.51%;经过12h连续电解,产甲酸法拉第效率仍高于67.81%,说明制备的SnO_(2)/γ-Al_(2)O_(3)粒子电极具有较强稳定性。

【Purposes】Electrocatalytic reduction of CO_(2)(CO_(2)RR)is a green and feasible solution to reduce the concentration of CO_(2) in the atmosphere.It is particularly important to prepare catalysts with high catalytic performance and stability.【Methods】The SnO_(2)/γ-Al_(2)O_(3) particle electrode was prepared by impregnation-calcination method withγ-Al_(2)O_(3) particles as carriers for electrocatalytic reduction of CO_(2) to produce formic acid.The microstructure,phase composition,electrocatalytic activity,formic acid production performance,and stability of the particle electrodes were investigated by means of physical and chemical analyses,electrochemical workstation measurements,and long-term experiments.【Findings】The results of physical and chemical analyses illustrate that the morphology of the particles before and after loading SnO_(2) changes from pores and cracks to cracked layers and the specific surface area increases from 310.18 to 352.70 m^(2)/g.Meanwhile,the Sn content is 48.32%in the prepared SnO_(2)/γ-Al_(2)O_(3) particle electrode.SnO_(2) is successfully dispersed on the surface ofγ-Al_(2)O_(3).According to the electrochemical test results,the voltammetric charge(scanning rate of 50 mV/s),exchange current density,and hydrogen evolution resistance of SnO_(2)/γ-Al_(2)O_(3) particle electrode are 40 mC,20.02μA/cm^(2),and 96.86Ω,respectively,which are 37.93%,75.46%,and 6.80%higher than those ofγ-Al_(2)O_(3),demonstrating the electrocatalytic activity of CO_(2) is greatly improved while the side reaction of hydrogen evolution is effectively inhibited.Furthermore,the SnO_(2)/γ-Al_(2)O_(3) particle electrode shows satisfactory CO_(2)RR characteristics,the production rate of formic acid is 70.35μmol·h-1·cm-2 and the current density is 4.94 mA/cm^(2) at the reaction time of 2 h,and the Faraday efficiency and energy efficiency are 79.05%and 24.51%respectively.After 12 h electrolysis experiment,the Faraday efficiency for formic acid production is still higher than 67.81%,indicating that the prepared SnO_(2)/γ-Al_(2)O_(3) particle electrode is strongly stable for long-term CO_(2) reduction.