Catalytic reduction of carbon dioxide to methanol over defect-laden hexagonal boron nitride: insights into reaction mechanisms

Abstract

We present a density functional theory-based mechanistic understanding of CO₂hydrogenation to value-added products on a nitrogen-vacancy (V_N) defect in hexagonal boron nitride (dh-BN). Activation occurs through back-donation to theπ* orbitals of CO₂from the frontier orbitals (defect state) of theh-BN sheet that are localized near a nitrogen-vacancy. Subsequent hydrogenation to methanol (CH₃OH) and formic acid (HCOOH) proceed through vacancy-facilitated co-adsorption of hydrogen and CO₂. More importantly, our reaction pathway analyses complimented by microkinetic modeling indicate thatdh-BN is potentially a low-temperature, selective catalyst for CO₂reduction to methanol. Our findings are in agreement with experiments conducted in a mechanical reactor that show high selectivity towards methanol formation for CO₂hydrogenation on defect inducedh-BN.

Keywords: CO2 reduction; boron nitride; density functional theory; formic acid; mechanocatalysis; methanol; reaction mechanisms.