Kormányos Attila, Szirmai Adrienn, Endrődi Balázs, Janáky Csaba
Department of Physical Chemistry and Materials Science, University of Szeged, Aradi sq. 1, Szeged 6720, Hungary.
ACS Catal. 2024 Apr 13;14(9):6503-6512. doi: 10.1021/acscatal.3c05952. eCollection 2024 May 3.
Despite the considerable efforts made by the community, the high operation cell voltage of CO electrolyzers is still to be decreased to move toward commercialization. This is mostly due to the high energy need of the oxygen evolution reaction (OER), which is the most often used anodic pair for CO reduction. In this study, OER was replaced by the electrocatalytic oxidation of glycerol using carbon-supported Pt nanoparticles as an anode catalyst. In parallel, the reduction of CO to CO was performed at the Ag cathode catalyst using a membraneless microfluidic flow electrolyzer cell. Several parameters were optimized, starting from the catalyst layer composition (ionomer quality and quantity), through operating conditions (glycerol concentration, applied electrolyte flow rate, etc.), to the applied electrochemical protocol. By identifying the optimal conditions, a 75-85% Faradaic efficiency (FE) toward glycerol oxidation products (oxalate, glycerate, tartronate, lactate, glycolate, and formate) was achieved at 200 mA cm total current density while the cathodic CO formation proceeded with close to 100% FE. With static protocols (potentio- or galvanostatic), a rapid loss of glycerol oxidation activity was observed during the long-term measurements. The anode catalyst was reactivated by applying a dynamic potential step protocol. This allowed the periodic reduction, hence, refreshing of Pt, ensuring stable, continuous operation for 5 h.
尽管该领域已付出巨大努力，但为了实现商业化，CO电解槽的高工作电池电压仍有待降低。这主要是由于析氧反应（OER）所需能量较高，而OER是CO还原反应中最常用的阳极反应对。在本研究中，使用碳载Pt纳米颗粒作为阳极催化剂，将甘油的电催化氧化反应替代了OER。同时，在Ag阴极催化剂上利用无膜微流体流动电解槽将CO还原为CO。从催化剂层组成（离聚物质量和数量）开始，到操作条件（甘油浓度、施加的电解液流速等），再到施加的电化学协议，对多个参数进行了优化。通过确定最佳条件，在总电流密度为200 mA cm时，对甘油氧化产物（草酸盐、甘油酸盐、酒石酸盐、乳酸盐、乙醇酸盐和甲酸盐）的法拉第效率（FE）达到了75 - 85%，而阴极CO生成的FE接近100%。在静态协议（恒电位或恒电流）下，长期测量过程中观察到甘油氧化活性迅速丧失。通过应用动态电位阶跃协议使阳极催化剂重新活化。这使得Pt能够周期性还原，从而得以更新，确保了5小时的稳定连续运行。
