Increasing the amount of accessible active sites to reactants is an effective way to enhance electrocatalytic activity. Although single-atom catalysts are claimed to be capable of achieving 100% atomic utilization, there may be abundant single-atom sites buried and inaccessible to reactants in practice. Herein, two Ni, N-doped carbon catalysts with Ni-N_x atomic sites are comparatively studied for CO₂ electroreduction. In contrast to the Ni-N_x/Carbon nanosheets with Ni loading of 2.42 wt%, the Ni-N_x/Carbon black with lower Ni loading of 0.16 wt% excitingly exhibits higher activity for CO production. The atomically dispersed Ni-Nx sites over carbon black surface benefit the exposure and utilization of single-atom sites, leading to a significant increase of TOF from 2140 to 100,347 h⁻¹ at − 0.8 V. Particularly, an extraordinarily high current density up to 300 mA cm⁻² with CO selectivity of ∼100 % are achieved for Ni-N_x/CB in the flow cell. This work demonstrates the significance of increasing single-atom site utilization.

增加反应物可及活性位点的数量是提高电催化活性的有效途径。尽管单原子催化剂声称能够实现 100% 的原子利用率，但在实践中可能有大量的单原子位点被掩埋并且反应物无法接近。在此，比较研究了两种具有Ni-N _x原子位点的Ni、N掺杂碳催化剂用于CO ₂电还原。_{与 Ni 负载量为 2.42 wt% 的 Ni-N x} /碳纳米片相比，Ni-N _x/具有 0.16 wt% 的较低 Ni 负载量的炭黑令人兴奋地表现出较高的 CO 生产活性。炭黑表面上原子分散的 Ni-Nx 位点有利于单原子位点的暴露和利用，导致 TOF 在 - 0.8 V 下从 2140 显着增加到 100,347 h -1 。特别是，极高的电流^密度高达流通池中的Ni-N _x /CB实现了300 mA cm ^{-2和 ~100% 的 CO 选择性。}这项工作证明了提高单原子位点利用率的重要性。