Dual hydrogen production from electrocatalytic water reduction coupled with formaldehyde oxidation via a copper-silver electrocatalyst

• Published in: Nature communications Vol. 14; no. 1; pp. 525 - 11
• Main Authors: Li, Guodong, Han, Guanqun, Wang, Lu, Cui, Xiaoyu, Moehring, Nicole K., Kidambi, Piran R., Jiang, De-en, Sun, Yujie
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31-01-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 639/301/299/161/886; 639/301/299/886; 639/638/161/886; 639/638/77/886; Cathodes; Copper; Density functional theory; Electric potential; Electrocatalysts; Electrolysis; Energy conversion efficiency; Formaldehyde; Humanities and Social Sciences; Hydrogen production; multidisciplinary; Oxidation; Oxygen evolution reactions; Science; Science (multidisciplinary); Silver; Voltage
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-36142-7

The broad employment of water electrolysis for hydrogen (H
2
) production is restricted by its large voltage requirement and low energy conversion efficiency because of the sluggish oxygen evolution reaction (OER). Herein, we report a strategy to replace OER with a thermodynamically more favorable reaction, the partial oxidation of formaldehyde to formate under alkaline conditions, using a Cu
3
Ag
7
electrocatalyst. Such a strategy not only produces more valuable anodic product than O
2
but also releases H
2
at the anode with a small voltage input. Density functional theory studies indicate the H
2
C(OH)O intermediate from formaldehyde hydration can be better stabilized on Cu
3
Ag
7
than on Cu or Ag, leading to a lower C-H cleavage barrier. A two-electrode electrolyzer employing an electrocatalyst of Cu
3
Ag
7
(+)||Ni
3
N/Ni(–) can produce H
2
at both anode and cathode simultaneously with an apparent 200% Faradaic efficiency, reaching a current density of 500 mA/cm
2
with a cell voltage of only 0.60 V.
Water electrolysis typically requires a large voltage input and produces H
2
only at the cathode. Here the authors present a strategy of coupling formaldehyde oxidation with water reduction and report H
2
production at both anode and cathode with small voltage inputs.