Facet-Engineered Copper Electrocatalysts Enable Sustainable NADH Regeneration with High Efficiency
Shuo Sun, Yizhou Wu, Yunxuan Ding, Linqin Wang, Xing Cao, Licheng Sun
Abstract
Electrochemical regeneration of the nicotinamide cofactor (NADH) provides a sustainable approach to enzymatic reactions. However, the low productivity and selectivity of bioactive 1,4-NADH limit its broad applications. The hydrogenation of NAD + to 1,4-NADH at the electrode surface is strongly coupled to the conformation of adsorbed NAD*, the formation of adsorbed hydrogen (H ad ), and the H ad transfer to NAD*. Therefore, searching for materials with a suitable NAD* conformation, low H ad formation energy, and rapid NAD* hydrogenation becomes a key task for the research. In this study, the (111) facet of Cu was found to exhibit a higher 1,4-NADH selectivity of 86.4%, compared to 50.4% and 57.4% for (100) and (110) facets, respectively. Density functional theory (DFT) calculations revealed that the high selectivity of Cu(111) stemmed from the favorable conformation of adsorbed NAD* and the reduced hydrogenation barrier. Subsequently, a Cu nanowire electrode with a (111)-dominant surface and abundant grain boundaries, Cu gb (111), was constructed. Electrochemical kinetic analysis and DFT calculations demonstrated that the grain boundaries reduce the reaction barrier of H ad formation. A record-high 1,4-NADH productivity of 73.5 μmol h –1 cm –2 was achieved by Cu gb (111), while the 1,4-NADH selectivity was well-maintained at 84.7%. This study elucidates the effects of crystal facets and grain boundaries on regulating the selectivity and productivity of 1,4-NADH, providing a pathway for renewable energy-powered, high-efficiency green biomanufacturing.