o-B2N2: a promising metal-free photocatalyst for highly efficient conversion of CO2 to hydrocarbons

Abstract

This study presents an efficient photocatalytic approach for CO₂ reduction, targeting the production of value-added products to enhance renewable energy and environmental sustainability. We focus on the recently predicted orthorhombic boron nitride (o-B₂N₂) phase, a two-dimensional monolayer polymorph of boron nitride which exhibits a direct band gap of 0.78 eV, making it a promising candidate for photocatalytic applications due to its favorable electronic properties. We examine pristine as well as the defective o-B₂N₂ as photocatalysts for CO₂ reduction reactions (CO₂RR). First-principles calculations show that pristine o-B₂N₂ interacts only weakly with CO₂, while the defective o-B₂N₂ significantly improves CO₂ adsorption, with an adsorption energy of −3.75 eV. Our investigation of the CO₂RR mechanism includes two pathways: the formate (*OCOH) pathway and the carboxylic (*COOH) pathway. The formate pathway involves the conversion of *OCOH into *HCOOH with a limiting potential (U_L) of 1.10 V for the formation of CH₃OH. Our result indicates OCOH* path to be most favorable for the CH₃OH production. These findings suggest that defective o-B₂N₂ is a highly effective catalyst for producing CH₃OH from CO₂.