Light Promotion and Different Reaction Pathways Enhance Photothermocatalytic Syngas Production for Cellulose Steam Reforming Over Ni/θ‐Al2O3

Abstract The photothermocatalytic cellulose steam reforming strategy has provided a sustainable approach, directly converting the largest renewable carbon resource (biomass), into syngas (H 2 and CO) which are clean and high‐value‐added energy carriers. However, this strategy for achieving high catalytic efficiency inevitably produces char, resulting in rapid deactivation and difficult recovery of catalysts, impeding industrial application. Herein, the Ni NPs (nanoparticles) loaded on θ ‐phase Al 2 O 3 (Ni/ θ‐ Al 2 O 3 ) catalyst enable efficient conversion of char generated during photothermocatalytic cellulose steam reforming process, thereby exhibiting high production rates of syngas (H 2 3776.3 and CO 2028.1 mmol h −1 ) and excellent durability (no deactivation after 4 cycles). Compared with a reference catalyst of Ni NPs loaded on amorphous SiO 2 (Ni/am‐SiO 2 ), this study finds that the elementary step of char conversion with H 2 O to syngas can be enhanced on Ni/ θ‐ Al 2 O 3 . With an emphasis on the mechanism, a different pathway is discovered that surface hydroxyl groups participating in the formation of HCO * intermediates, further dissociating to syngas, significantly facilitate the conversion of char. Additionally, on Ni/ θ‐ Al 2 O 3 , the photoactivation effect enhances catalytic activity, particularly promoting the conversion of H 2 O with char to syngas, thus preventing deactivation caused by encapsulation of char.