The electrochemical CO 2 reduction reaction (CO 2 RR) represents a viable alternative to help close the anthropogenic carbon cycle and convert intermittent electricity from renewable energy sources to chemical energy in the form of value-added chemicals. The development of economic catalysts possessing high faradaic efficiency (FE) and mass activity (MA) toward CO 2 RR is critical in accelerating CO 2 utilization technology. Herein, an elaborate Au−Cu catalyst where an alloyed AuCu shell caps on a Cu core (Cu@AuCu) is developed and evaluated for CO 2 -to-CO electrochemical conversion. Specific roles of Cu and Au for CO 2 RR are revealed in the alloyed core−shell structure, respectively, and a compositional-dependent volcano-plot is disclosed for the Cu@AuCu catalysts toward selective CO production. As a result, the Au 2 −Cu 8 alloyed core−shell catalyst (only 17% Au content) achieves an FE CO value as high as 94% and an MA CO of 439 mA/mg Au at −0.8 V (vs RHE), superior to the values for pure Au, reflecting its high noble metal utilization efficiency.

Appropriate dispersants for the dispersion of gallium zinc oxide (GZO) nanopowder in aqueous suspensions were identified in this study. The dispersion efficiencies and stabilization mechanisms of water‐based dispersants ammonium poly(acrylic acid) (PAA–NH4), an anionic polyelectrolyte, and polyethylenimine (PEI), a cationic polyelectrolyte, were compared. The experimental analyses of rheology and sedimentation showed that both PAA–NH4 and PEI were good dispersants for the dispersion of GZO. Theoretical calculations based on Derjaguin‐Landau‐Verwey‐Overbeek theory revealed that the stabilization mechanism of PEI was mainly related to the steric effect, and a very low molecular weight of 1800 g/mol was insufficient for powder stabilization. GZO was well dispersed by PEI with high molecular weight of 10 000 g/mol, but agglomeration occurred when too much PEI was added. Compared with PEI, PAA–NH4 was more efficient because of its high contribution to the increase in electrostatic repulsion. Based on theoretical considerations on both steric and electrostatic effects, namely, the electrosteric stabilization mechanism, PAA–NH4 is optimal for the dispersion of GZO nanopowder in aqueous suspensions.