Synergy effects on Sn-Cu alloy catalyst for efficient CO2 electroreduction to formate with high mass activity

高质量活性Sn-Cu合金协同催化CO2电还原制备甲酸

To acquire the synergy effects between Sn and Cu for the jointly high Faradaic efficiency and current density,we develop a novel strategy to design the Sn-Cu alloy catalyst via a decorated co-electrodeposition method for CO2 electroreduction to formate.The Sn-Cu alloy shows high formate Faradaic efficiency of 82.3%±2.1% and total C1 products Faradaic efficiency of 90.0%±2.7% at^-1.14 V vs.reversible hydrogen electrode(RHE).The current density and mass activity of formate reach as high as(79.0±0.4)mA cm^-2 and(1490.6±7.5)m A mg^-1 at^-1.14 V vs.RHE.Theoretical calculations suggest that Sn-Cu alloy can obtain high Faradaic efficiency for CO2 electroreduction by suppressing the competitive hydrogen evolution reaction and that the formate formation follows the path of CO2→HCOO*→HCOOH.The stepped(211)surface of Sn-Cu alloy is beneficial towards selective formate production.

CO2电化学还原反应(CO2RR)为可再生能源储存及CO2转化提供了有效途径.目前,CO2转化为C1化学品(如甲酸和CO等)被认为是CO2RR最可行的途径之一.甲酸具有高的氢含量及易于存储和运输等特点,通常被用作燃料电池的液体燃料.目前,Sn、Cu、In、Bi等金属作为CO2RR制备甲酸的催化剂被广泛报道,但是这些催化剂的选择性和质量活性即使在高的过电位下仍然不佳.因此,将Sn或Cu与其他元素合金化是提高CO2RR质量活性的有效方法,通过调整合金表面电子结构来调节反应中间体的结合能,可以达到提高CO2RR性能的目的.本文利用修饰的电化学共沉积法一步制备了Sn-Cu合金催化剂,并提高其CO2RR质量活性.在^-1.14V(vs.RHE)电位下,Sn-Cu合金的甲酸法拉第效率为82.3%±2.1%,甲酸产物的质量活性达到(1490.6±7.5)mA mg^-1,且具有良好的稳定性.理论计算表明,Sn-Cu合金通过抑制竞争性的析氢反应来获得高的甲酸法拉第效率.甲酸生成路径为CO2→HCOO*→HCOOH,Sn-Cu合金的(211)台阶表面有利于选择性地生成甲酸.