Manipulating adsorbed hydrogen on lanthanum-modified CuOx: Industrial-current-density CO2 electroreduction to C2+ products or CH4

The selective electrochemical CO 2 reduction reaction (CO 2 RR) yields valuable C 2+ and C 1 products, yet the influence of adsorbed hydrogen (*H) on product distribution remains inadequately understood. This study explores this effect by developing bimetallic copper-based electrocatalysts with varied lanthanum (La) doping ratios. The oxide-derived (OD)-La 0.10 -CuO x catalyst exhibits a Faradaic efficiency (FE) over 80% for C 2+ products at 300 mA cm −2 , whereas OD-La 0.40 -CuO x achieves a 61.4% FE CH4 at 400 mA cm −2 . Kinetic isotope experiments reveal distinct dependencies of the rate-determining steps on *H transfer for CO 2 RR in OD-La 0.10 -CuO x and OD-La 0.40 -CuO x . In situ ATR-SEIRAS and DFT calculations demonstrate that the moderate H 2 O dissociation capability of OD-La 0.10 -CuO x lowers the energy barrier for *CHO → *OCCHO conversion, thus increasing the FE C2+ . Conversely, OD-La 0.40 -CuO x , with its strong H 2 O dissociation capability, favors *CHO → *CH 2 O, thereby promoting CO 2 RR-to-CH 4 . These findings advance the understanding of the role of *H in CO 2 electroreduction at industrial current densities and present avenues for tailored CO 2 RR products via doping engineering. Tuneable electrochemical CO 2 dimerization to C 2+ products or hydrogenation to CH 4 is achieved by adjusting the adsorbed hydrogen on La-CuO x catalysts with different La-doping ratio. • Selective CO 2 RR to C 2+ or CH 4 is achieved by tuning La doping in La-CuO x catalysts. • La doping enhances H 2 O dissociation capacity, increasing surface-adsorbed hydrogen. • Adsorbed hydrogen manipulates *CHO dimerization to C 2+ and hydrogenation to CH 4 . • OD-La 0.10 -CuO x achieves FE > 80% for C 2+ through enhanced *CHO dimerization to *OCCHO. • OD-La 0.40 -CuO x achieves FE > 60% for CH 4 through enhanced *CHO hydrogenation to *CH 2 O.