Influence of Composition, Layer Thickness, and 2D Layer Coupling on Electrochemical Manufacturing
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The electrochemical reduction of CO 2 to hydrocarbon and oxygenate products has been demonstrated over metal-based catalysts such as Cu, but achieving high Faradaic efficiency (FE) has been a bottleneck. Here, we address this challenge by investigating how metal and C-N composition, layer thickness, and 2D heterostructure coupling influence CO 2 activation and product selectivity in emerging 2D materials. A suite of MXenes and related 2D heterostructures, Ti 2 NT x , Ti 4 N 3 T x , Ti 3 CNT x , V 2 NT x , V 2 CT x , MoS 2 /Ti 2 NTₓ and MoS 2 /Ti 4 N 3 T x were synthesized via a top-down etching method and evaluated for CO₂RR alongside the competing hydrogen evolution reaction (HER). Ti-based nitrides exhibited minimal CO 2 RR activity and strongly favored HER, with layer thickness and MoS₂ coupling showing little effect. Introducing both C and N into Ti 3 CNT x improved performance, yielding FE(CO) ~ 25–30% and FE(HCOOH) ~ 8–10%. A more substantial enhancement arose from changing the metal center: V-based MXenes shifted the reaction pathway toward CO 2 RR, with V 2 NT x achieving FE(CO) ~ 50% and FE(HCOOH) ~ 18%, outperforming V 2 CT x and suppressing HER at moderate current densities. V-based materials also displayed stability over hours with no loss in CO selectivity. Across all catalysts, CO and HCOOH were the only carbon-based products, indicating high intrinsic selectivity. Overall, this study elucidates the fundamental roles of composition, stoichiometry, and 2D structural coupling in governing CO 2 RR behavior, providing insights for designing next-generation catalysts for interfacial electrochemical reactions.
