The electrocatalytic reduction of industrially diluted CO2 streams (5-30%) represents a pivotal avenue for carbon resource utilization. However, its practical implementation has long been hindered by mass transfer limitations and competitive hydrogen evolution reactions under low CO2 concentrations. Current research has largely focused on pure CO2 systems, overlooking the mechanistic intricacies of *CO intermediate dynamics and C-C coupling efficiency in CO2-deficient environments. To address this challenge, this study developed compositionally tunable core-shell Ag@(Cu2O)x catalysts via a seed-mediated growth approach, enabling precise modulation of the Cu2O/Ag ratio (x = 0.14-5.0) to optimize the interplay between *CO intermediates and C-C coupling under diluted conditions. Notably, experimental results demonstrate that the Ag-rich Ag@(Cu2O)0.75 catalyst achieves a Faradaic efficiency for ethylene (FEC2H4) exceeding 45% under 25% CO2. While the Cu2O-rich Ag@(Cu2O)3.0 catalyst, although optimal in pure CO2 systems, fails under the same diluted conditions due to insufficient *CO supply. This discovery underscores the pivotal role of *CO supply in dictating the overall catalytic efficiency and product distribution pathways during low-concentration CO2 electrocatalytic processes.
Zhu et al. (Fri,) studied this question.