Green Syngas from Photothermal Catalytic Cellulose Steam Reforming on Ni/SiO₂ Nanocatalysts: Synergy of La³+ Promotion and Ni-O Photoactivation

Abstract

Replacing fossil fuels by renewable biomass enables green syngas production in an effort to achieve carbon neutrality and sustainable circular processes. Here, an inexpensive catalyst of Ni nanoparticles supported on SiO2 modified by La3+ (Ni/La0.10-S) is presented, exhibiting exceptional H2 and CO production rates (4051.4 and 2467.8 mmol gcatalyst -1 h-1, respectively) with 7.7% light-to-fuel efficiency in cellulose steam reforming (SR), merely under focused illumination. Excellent performance is mainly attributed to photothermal catalysis resulting from the strong solar absorption and high photothermal conversion by the Ni nanoparticles. The mitigation of tar and char formation significantly benefits from the H2O involvement in the reaction, which is substantially improved by La3+ addition enhancing H2O sorption. Remarkably, the illumination exerts mere photoactivation during reaction, which is primarily attributed to the pronounced activation of Ni─O bonds at the catalyst surface. Particularly, the photoactivation of the Ni-O-La moieties, in combination with O species replenishment by H2O, makes Ni/La0.10-S superior to Ni/SiO2. The synergy of La3+ promotion and Ni-O photoactivation poses a promising strategy for efficient photothermal catalytic cellulose SR to green syngas.