调节CuPd催化剂的中间反应势垒以提高CO2电还原为C2产物的选择性
Tuning the intermediate reaction barriers by CuPd catalyst to improve the selectivity of electroreduction CO2 to C2 products
摘要：
电化学CO2还原是利用CO2和间歇性过剩电力的一种有前途的策略。铜是唯一可以将二氧化碳电化学转化为多碳产物的单金属催化剂。然而，Cu对于C2产物具有不期望的选择性和活性，这是由于其用于C-C偶联的CO* 的量不足。考虑到Pd对CO2的强吸附和CO* 生成的超快反应动力学，设计了一种紧密的CuPd（100）界面，以降低中间反应势垒，从而提高C2产物的效率。密度泛函理论（DFT）计算表明，CuPd（100）界面增强了CO2的吸附，降低了CO2* 加氢能垒，有利于C-C偶联. CuPd（100）界面上CO2生成C2产物的电位决定台阶（PDS）势垒为0.61 eV，低于Cu（100）界面上的电位决定台阶（0.72 eV）。在DFT计算的启发下，采用简单的化学溶液法制备了CuPd（100）界面催化剂，并用透射电子显微镜（TEM）对其进行了表征。CO2程序升温脱附（CO2-TPD）和气敏实验证实了CuPd（100）界面催化剂对CO2的吸附和加氢性能的增强。结果，所获得的CuPd（100）界面催化剂在0.1M KHCO 3中在-1.4VRHE下表现出50.3（+/-）± 1.2%的C2法拉第效率，这比Cu催化剂的23.6（+/-）± 1.5%高2.1倍。本工作通过微调中间反应势垒，为多碳产物铜基电催化剂的合理设计提供了依据。
英文摘要：
Electrochemical CO2 reduction is a promising strategy for utilization of CO2 and intermittent excess electricity. Cu is the only single-metal catalyst that can electrochemically convert CO2 to multi-carbon products. However, Cu has an undesirable selectivity and activity for C2 products, due to its insufficient amount of CO* for C-C coupling. Considering the strong CO2 adsorption and ultra-fast reaction kinetics of CO* formation on Pd, an intimate CuPd(100) interface was designed to lower the intermediate reaction barriers and then improve the efficiency of C2 products. Density functional theory (DFT) calculations showed that the CuPd(100) interface has enhanced CO2 adsorption and decreased CO2* hydrogenation energy barrier, which are beneficial for C-C coupling. The potential-determining step (PDS) barrier of CO2 to C2 products on CuPd(100) interface is 0.61 eV, which is lower than that on Cu(100) (0.72 eV). Motivated by the DFT calculation, the CuPd(100) interface catalyst was prepared by a facile chemical solution method and demonstrated by transmission electron microscope (TEM). The CO2 temperature programmed desorption (CO2-TPD) and gas sensor experiments proved the enhancements of CO2 adsorption and CO2* hydrogenation abilities on CuPd(100) interface catalyst. As a result, the obtained CuPd(100) interface catalyst exhibits a C2 Faradaic efficiency of 50.3 (+/-) 1.2% at -1.4 VRHE in 0.1 M KHCO3, which is 2.1 times higher than 23.6(+/-) 1.5% of Cu catalyst. This work provides a rational design of Cu-based electrocatalyst for multi-carbon products by fine-tuning the intermediate reaction barriers.
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