Sungjin Park, Hengzhou Liu, Heejong Shin, Hafiz Ghulam Abbas, Loann Bonnenfant, Ke Xie, Hyeon Seok Lee, Fatemeh Arabyarmohammadi, Jianan Erick Huang, Panos Papangelakis, Peiying Wang, Ali Shayesteh Zeraati, Jiheon Kim, Roham Dorakhan, David Sinton, Xiaopeng Liu, Wenzhen Li, Byoung-Hoon Lee, Edward H Sargent
Electrochemical upgrading from CO2 and CO to ethylene has typically been coupled with the oxygen evolution reaction (OER), whose high standard reduction potential leads to full-cell voltages above 2.2 V at 200 mA/cm2. Here we explored an alternative anodic reaction, where furfural is oxidized to furoic acid, a reaction having a low onset potential (E0 ≈ 0.05 V vs. RHE), and which reaction is accompanied by the evolution of H2: an anodic hydrogen evolution reaction (a-HER). In early experiments, copper oxide as a-HER catalyst exhibit limited stability (< 10 min) and activity (80 mA/cm2 at 0.8 Vcell). We found, using operando spectroscopy, that hydroxide forms on the surface of copper and deactivates the desired a-HER process. When we screened candidate metal dopants, we found the best to be Au, for it served to stabilize the Cu surface, enablinained a-HER: 260 mA cm-2 at 0.8 Vcell and stable operation for 16 h. Integrated into a paired CO-to-ethylene electrolyzer, this delivered 0.92 Vfullcell at 400 mA cm-2, required 40 GJ electricity per ton of ethylene, and co-produced 460 kg H2 per ton ethylene. To enable comparison with CO2-to-ethylene reports, which require an additional CO2-to-CO step, we estimate ∼ 69 GJ/tonC2H4.