A review of boron nitride-based photocatalysts for carbon dioxide reduction

Abstract

The conversion of carbon dioxide (CO₂) into valuable chemicals by photoreduction is an effective strategy for tackling the global warming conundrum. However, highly efficient use of traditional metallic species as co-catalysts is challenging as they are photo-corroded, thereby causing leaching of dopant metals and deactivation of the photocatalysts. To address these issues, two-dimensional (2D) nanomaterials, including MXenes, transition metal dichalcogenides, and layered nanomaterials, with promising properties, such as high chemical tunability and appropriate catalytic activity, have been developed for CO₂ photoconversion. Among them, non-metallic boron nitride (BN), with a unique capability to transfer electrons through B–N channels with a high electronegativity difference, can efficiently facilitate the CO₂ reduction reaction. However, modification strategies are required for BNs to be effective in photoreduction, mainly owing to their large band gaps, causing them to be excited in the UV region (mere 4% of the solar spectrum), and their inert surface chemistry. Thus, considerable interdisciplinary studies have been conducted on morphology regulation, surface engineering, and optoelectronic tailoring of these photocatalysts in conjunction with advanced characterisation techniques and density functional theory calculations. This review discusses the mechanisms and reaction pathways for the reduction of CO₂ by BN nanotubes and nanosheets. Additionally, state-of-the-art modification techniques, including doping with organic and inorganic compounds, fabricating composite heterojunctions, and engineering defects to tailor CO₂ adsorption/conversion, are summarised. In the end, the challenges associated with the large-scale production, stability, and product selectivity of BN are enlightened, accompanied by the final concluding remarks and suggestions for future studies. The development of a sustainable approach for producing stable and modified BNs suggests visible-light-responsive semiconductors that not only reveal their potential for CO₂ conversion, but can also be utilised for other prospective photocatalytic applications.