Atomically Dispersed Copper in TiO 2 Supported NiO Nanoparticles Drives High CH 4 Productivity, Selectivity, and Stability in CO 2 Methanation Via Reversible Oxygen Vacancies Generation

Abstract

Designing efficient and durable catalysts for CO 2 methanation remains a critical challenge for sustainable energy conversion. Here, we report a TiO 2 -supported NiO catalyst incorporating atomically dispersed copper species (1 wt.%), denoted as NiO-Cu1, that delivers exceptional CH 4 productivity of 28,497 mmol g⁻¹ h⁻¹ at 300 °C with 92.5% CH 4 selectivity, outperforming its monometallic counterpart NiO-TiO 2 (12,482 mmol g⁻¹ h⁻¹) by 128%. More importantly, NiO-Cu1 exhibits outstanding durability, maintaining 100% stability over 300 thermal cycles corresponding to 495 hours of continuous operation. X-ray photoelectron spectroscopy (XPS) analysis reveals that atomic copper dispersion generates abundant oxygen vacancies in the NiO. Furthermore, in situ X-ray absorption spectroscopy (XAS) and ambient pressure X-ray photoelectron spectroscopy (APXPS) uncover that these oxygen vacancies are reversible in nature and play a key role in CO 2 activation, while adjacent NiO sites facilitate H 2 dissociation. This synergistic interplay between copper-induced reversible oxygen vacancies and NiO active sites enables highly productive, selective, and durable CO 2 -to-CH 4 conversion, positioning NiO-Cu1 as a promising platform for next-generation power-to-gas technologies.