Single-layer CoMoS anchored on reduced graphene oxide for efficient and stable hydrodeoxygenation of lignin-derived phenolics to arenes.

Achieving both high activity and good stability remains a challenge for the design of MoS-based catalysts in the hydrodeoxygenation (HDO) reaction. Herein, a robust catalyst with single-layer CoMoS anchored on hydrophobic reduced graphene oxide (SL-CoMoS/rGO) was fabricated, which exhibited high activity, selectivity and excellent stability in the HDO of lignin-derived phenolics to arenes. Utilizing the HDO of 4-methylphenol as a probe reaction, the catalyst afforded a conversion of 98.3 % and a toluene selectivity of 99.2 % at a mild condition of 210 °C and 3.0 MPa. The superior HDO performance was ascribed to the high dispersion of MoS particles, which provides a large amount of edge sites for the efficient Co decoration to form the Co-Mo-S active centers. Thus, the Mo-S bond at the edge sites was significantly weakened and the formation of sulfur vacancies was remarkably enhanced. Besides, density functional theory calculations reveal that Co-Mo-S active phase could not only favor the adsorption of 4-methylphenol but also lower the energy barrier of the rate-determining step. Moreover, no obvious deactivation was observed for SL-CoMoS/rGO after six HDO cycles. The excellent durability was benefitted from the hydrophobic surface and lowered reaction temperature, which could effectively alleviate the sulfur loss and particle sintering.