Photocatalytic Reforming of Biomass Derived Crude Glycerol in Water: A Sustainable Approach for Improved Hydrogen Generation Using Ni(OH)₂ Decorated TiO₂ Nanotubes under Solar Light Irradiation

Abstract

Crude glycerol (10% w/w) is produced as a substantial byproduct during the industrial production of biodiesel via transesterification processes. Catalytic hydrogen (H 2 ) generation by utilizing crude glycerol and solar light is considered as a promising avenue. The present work illustrates enhanced rates of H 2 generation and cocatalyst behavior of Ni(OH) 2 decorated on TiO 2 nanotubes dispersed in aqueous crude glycerol solution (industrial byproduct) under solar light irradiation. The catalyst characterization reveals that the TiO 2 nanotubes (TNT) are of anatase phase with length ranges from 100 to 300 nm and diameters from 4.9 to 9.8 nm. The Ni(OH) 2 quantum dots deposited on TNT have an average particle size of 8.4 nm. The presence of Ni(OH) 2 on TNT and oxidation states of Ti 4+ and Ni 2+ cations are confirmed by XPS analysis. The optimal loading of Ni (2.0 wt %) leads to a high rate of photocatalytic H 2 generation of 4719 μmol h −1 g cat −1 and it is ∼12-fold higher than pristine TNT. The solar light energy conversion efficiency of the optimized catalyst and cost benefit analysis by using crude glycerol are also evaluated. The high electronegativity of Ni(OH) 2 quantum dots present on the surface of TNT may facilitate effective shuttling of photoexcitons, thereby largely preventing electron−hole recombination in TiO 2 during photocatalysis.

Recent progresses in photocatalytic hydrogen production: design and construction of Ni‐based cocatalysts

“…The results show that the enhanced photocatalytic activity originated from the introduction of Ni(OH) 2 nanoparticles, which unfolds a co‐catalytic property. In addition, Reddy and co‐workers 90 found that crude glycerol could be reformed to generate hydrogen by TiO 2 nanotubes modified with Ni(OH) 2 QDs under solar light irradiation, as presented in Figure 4A. It is interesting that the high electronegativity of Ni(OH) 2 material could intensify the shuttling of photoexcitons, so as to enhance the photocatalytic hydrogen production performance.…”

“…(A) Plausible reaction mechanism for H 2 generation on Ni(OH) 2 /TNT from crude glycerol 90 . (B) Schematic illustration of the photoinduced fabrication of Pt/Ni(OH) 2 ‐C 3 N 4 86 [Colour figure can be viewed at wileyonlinelibrary.com]…”

Solar hydrogen generation from organic substance using earth abundant CuS–NiO heterojunction semiconductor photocatalyst

“…Modified wet impregnation route was adapted to disperse the NiO co-catalyst nanoparticles on CuS photocatalyst [29]. Typically, 0.5 g of Polyvinylpyrrolidone ((C6H9NO)n average mol.…”

“…The experimental process followed for photocatalytic hydrogen evolution and processing parameters used in gas chromatography for accurate quantification of hydrogen gas was followed as in our recent publication [29]. The pristine CuS, NiO and composite CuS/NiO (CPN-1, CPN-2 and CPN-3) were firstly tested in photocatalytic water splitting experiments under nature Sunlight irradiation.…”

The Role of Common Alcoholic Sacrificial Agents in Photocatalysis: Is It Always Trivial?

“…[16] The hole in the TiO 2 valence band has a highly positive potential of + 2.95 V versus NHE. Moreover, because photocatalytic H 2 production is part of the overall sustainability research, the utilization of biomass-derived alcohols (e. g., methanol, [17] ethanol, [18] glycerol, [19] and formaldehyde [20] ) as sacrificial (electron) donors has recently become an attractive green route for H 2 production. [18] The overall catalytic H 2 evolution is a complex process that is under ongoing research.…”