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

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 (UL) 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.