Marked enhancement of electrocatalytic activities for gas-consuming reactions by bimodal mesopores

Abstract

Electrochemically catalytic conversions have attracted worldwide interest as promising routes to reach a sustainable and green energy cycle. The exploration of efficient electrocatalysts is one of the key tasks, in which the majority has focused on devising new active centers; however, mass transport that determines the reactant supply and the conductance of electrolyte ions and electrons is often overlooked. Here, we report on spatially locating active centers into parallelly bimodal mesopores by precisely engineering mesopore geometries, through which the contribution of the paralleled transport channels to the activity of gas-consuming reactions was quantitatively determined. Under identical conditions, bimodal mesoporous carbon-based electrocatalysts displayed a 2.9 times higher CO partial current density than monomodal mesoporous catalysts for CO₂-to-CO conversion in the kinetic region of −1.1 V vs. RHE. Likewise, the strong correlation between the activity enhancement and the bimodal mesopore geometry was verified for supported molecular catalysts and applicable to other gas-consuming reactions such as the O₂ reduction reaction. These encouraging results offer a fresh and general idea to advance electrocatalysts by pore geometry engineering on the mesoscale.