Lattice-Hydride Mechanism in Electrocatalytic CO₂ Reduction by Structurally Precise Copper-Hydride Nanoclusters

Abstract

Copper electrocatalysts can reduce CO to hydrocarbons at high overpotentials. However, a mechanistic understanding of CO reduction on nanostructured Cu catalysts has been lacking. Herein we show that the structurally precise ligand-protected Cu-hydride nanoclusters, such as CuHL (L is a dithiophosphate ligand), offer unique selectivity for electrocatalytic CO reduction at low overpotentials. Our density functional theory (DFT) calculations predict that the presence of the negatively charged hydrides in the copper cluster plays a critical role in determining the selectivity of the reduction product, yielding HCOOH over CO with a lower overpotential. The HCOOH formation proceeds via the lattice-hydride mechanism: first, surface hydrides reduce CO to HCOOH product, and then the hydride vacancies are readily regenerated by the electrochemical proton reduction. DFT calculations further predict that hydrogen evolution is less competitive than HCOOH formation at the low overpotential. Confirming the predictions, electrochemical tests of CO reduction on the CuHL cluster demonstrate that HCOOH is indeed the main product at low overpotential, while H production dominates at higher overpotential. The unique selectivity afforded by the lattice-hydride mechanism opens the door for further fundamental and applied studies of electrocatalytic CO reduction by copper-hydride nanoclusters and other metal nanoclusters that contain hydrides.

Tailoring Surface Frustrated Lewis Pairs of In2O3−x(OH)y for Gas‐Phase Heterogeneous Photocatalytic Reduction of CO2 by Isomorphous Substitution of In3+ with Bi3+

“…The bond lengths and Bader charges for these two cases (b and c) and the unsubstituted surface are provided in Table 1 . It is also interesting to observe that the resulting hydride is more hydridic in both case b and case c. The extra negative charge on the hydride facilitates the charge transfer from the catalyst surface to CO 2 , causing the C—O bond to lengthen and break 42, 45, 48…”

Hydride Pinning Pathway in the Hydrogenation of CO2 to Formic Acid on Dimeric Tin Dioxide

“…[13,[36][37][38] On the Cu-hydride nanocluster, CO 2 reduction follows a different mechanism where CO 2 is activated in the influence of lattice hydride and forms a formate intermediate at an overpotential of 0.32 eV. [39] Herein, our investigation paves a new way of thinking about the hydride assisted pathway for the selective reduction of CO 2 to FA over metal oxide nanoparticles; we have built our understanding around the interaction of CO 2 and dissociation of H 2 on small SnO 2 monomers and dimers, and subsequently investigated a new and selective path for the conversion of CO 2 into formic acid.…”

Recent Progress in the Theoretical Investigation of Electrocatalytic Reduction of CO2

“…[114] A dethiolated site was necessary to Figure 11. [115] It is quite unique that the negatively charged hydrides (H − ) are located at the capping sites and/or the interstitial sites, thus might participate in the reduction leading to new mechanism. b) Distribution of CO binding energetics of randomly sampled sites on Cu NP surface.…”

“…c) *OCCOH generation process on the proposed surface sites with favored binding. [115] Copyright 2017, The American Chemical Society. Reproduced with permission.…”