Work

CH 4 Boosts the Atmospheric Nitrate-to-HONO Formation by Photoinduced • CH 3 Radicals

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The impact of rising CH 4 concentrations has become a key global focus in air pollution and climate change, as its photoconversion generates highly reactive methyl radicals with translational potential. However, the overlooked role of • CH 3 radicals on HONO formation has led to the underestimated contribution of greenhouse gases on atmospheric oxidative capacity. Here, we propose a CH 4 -promoted nitrate photolysis route where the nitrate-to-HONO is significantly promoted, varying from 46.98% to 95.75% as the relative humidity increased. In situ spectroscopic and theoretical analyses reveal that the • CH 3 radicals activate the NO 3 – molecule to facilitate N–O bond cleavage and promote H 2 O dissociation to supply hydrogen atoms for HONO formation, with pivotal • OH radicals from H 2 O further enhancing this effect under high RH conditions. We also roughly estimated the enhancement of the atmospheric • OH radical budget by CH 4 and confirmed its environmental significance through demonstrations on the surfaces of atmospheric fine particulate matter and industrial photoactive materials. This work underscores the interactive relationship between CH 4 and atmospheric oxidative capacity and provides direct evidence for the observed enhancement of atmospheric oxidative capacity contributed by greenhouse gases.

Source: Journal of the American Chemical Society

DOI: 10.1021/jacs.5c12556