Effect of Ball-Milling Pretreatment of Cellulose on Its Photoreforming for H₂ Production

Abstract

Photoreforming of cellulose is a promising route for sustainable H 2 production. Herein, ball-milling (BM, with varied treatment times of 0.5–24 h) was employed to pretreat microcrystalline cellulose (MCC) to improve its activity in photoreforming over a Pt/TiO 2 catalyst. It was found that BM treatment reduced the particle size, crystallinity index ( CrI ), and degree of polymerization ( DP ) of MCC significantly, as well as produced amorphous celluloses (with >2 h treatment time). Amorphous cellulose water-induced recrystallization to cellulose II (as evidenced by X-ray diffraction (XRD) and solid-state NMR analysis) was observed in aqueous media. Findings of the work showed that the BM treatment was a simple and effective pretreatment strategy to improve photoreforming of MCC for H 2 production, mainly due to the decreased particle size and, specifically in aqueous media, the formation of the cellulose II phase from the recrystallization of amorphous cellulose, the extent of which correlates well with the activity in photoreforming.

Photoreforming of Waste Polymers for Sustainable Hydrogen Fuel and Chemicals Feedstock: Waste to Energy

“…200 to 9.6 MWh·t –1 for milling at a 1 kg scale compared to a 1 g scale in planetary ball mill. These energy efficiencies and the potential reduction in the environmental impact − indicate that ball milling is a feasible pretreatment method for cellulose and has been used successfully as a pretreatment for the hydrolysis of cellulose to glucose ,, as well as for the activation of cement …”

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.…”

“…The main components of lignocellulosic biomass are cellulose (35–50%), hemicellulose (25–30%), and lignin (15–30%). 21,22 Cellulose, 23–28 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.…”

2023 roadmap on photocatalytic water splitting

“…For cellulose, the mechanism has been proposed to occur through (photo)hydrolysis of cellulose by the initial attack of OH radicals (generated from the reaction of water with photogenerated holes) on the cellulose chains generating smaller cellulose units, sugars and further oxidation products such as formic acid. The formation of such compounds could also more efficiently hinder the recombination of photogenerated e − and h + on the catalyst [106]. With continued optimisation, PC reforming of biomass (and biomass-derived) substrates has the potential to generate H 2 at <$1.5 USD Kg −1 [107] whilst utilising renewable energy.…”