Solar-Driven Photocatalytic Reforming of Lignocellulose into H₂ and Value-Added Biochemicals

Abstract

Lignocellulose is the most abundant form of biomass on earth, and its efficient valorization for H 2 generation and value-added biochemical production provides a promising strategy to alleviate the currently faced energy shortages. However, the requirements of toxic organic solvents, unsatisfactory conversion, and poor selectivity of biochemicals make the effective biomass photorefinery challenging. Herein, we report the efficient lignocellulose photoreforming including cellulose, hemicellulose, and lignin, using polymeric carbon nitride photocatalyst that was prepared via the pyrolysis of a preorganized supramolecular assembly between cyanuric acid, melamine, and Pt-(NH 2 -bpy) 2 . The optimized catalyst exhibits a superior H 2 evolution rate of 3.39 mmol g −1 h −1 from the aqueous glucose solution under irradiation of a 427 nm LED light source, which is more than nine times higher than that of the pristine carbon nitride. Furthermore, 100% conversion of glucose and 86% selectivity toward lactic acid are achieved with the system. Density functional theory calculations verify that the introduction of Pt significantly lowers the activation energy barrier for water reduction into hydrogen and facilitates the selective cleavage of the C−C bond of fructose generated by glucose isomerization, which is weakened by electron density shift to the adjacent bond, the essential step to promote lactic acid production. This work presents an effective and promising strategy to couple the H 2 generation and value-added biochemical production through biomass photorefinery.

Potassium and Sulfur Dual Sites on Highly Crystalline Carbon Nitride for Photocatalytic Biorefinery and CO2 Reduction

“…The above experimental analysis and the previous studies ,,− were combined to propose a possible mechanism for photocatalytic CO 2 reduction and oxidation of xylose via K/S@CN-0.5. As depicted in Figure S19, K/S@CN-0.5 possessed excellent light capture capabilities and produced photoexcited e – –h + under visible light irradiation.…”

Alternatives to water oxidation in the photocatalytic water splitting reaction for solar hydrogen production

“…The main components of lignocellulosic biomass are cellulose (35-50%), hemicellulose (25-30%), and lignin (15-30%). 21,22 Cellulose, [23][24][25][26][27][28] hemicellulose 24,29,30 and lignin 24,26,31,32 have been reported to produce H 2 using various photocatalysts such as TiO 2 , CdS/CdO x quantum dots, carbon dots, carbon nitride, and CdS (Table 1). Metallic nanoparticulate cocatalysts (e.g., Pt, Au, and Pd) and non-precious cocatalysts (e.g., NiP and NiS) are frequently loaded on the photosensitizers by wet impregnation and photodeposition methods, with Pt the most commonly studied.…”

Overall Utilization of Photoexcited Charges for Simultaneous Photocatalytic Redox Reactions

“…Nevertheless, the overuse of sacrificial agents contributes to a hazardous environment and needless economic burden. It is promising to replace the photooxidation of sacrificial agents with organic conversion or synthesis (Table 2) 102,[140][141][142][143][144][145][146] .…”