Abstract
The application of hybrid photocatalysts made of carbon nitride and lead-free perovskites, namely DMASnBr3/g-C3N4 and PEA2SnBr4/g-C3N4, for the H2 evolution from saccharides aqueous solution is described. The novel composites were tested and compared in terms of hydrogen evolution rate (HER) under simulated solar light, using Pt as a reference co-catalyst, and glucose as a representative sacrificial biomass. The conditions were optimized to maximize H2 generation by a design of experiments involving catalyst amount, glucose concentration and Pt loading. For both materials, such parameters affected significantly H2 photogeneration, with the best performance observed using 0.5 g L−1 catalyst, 0.2 M glucose and 0.5 wt% Pt. Under optimized conditions, DMASnBr3/g-C3N4 showed a 5-fold higher HER compared to PEA2SnBr4/g-C3N4, i.e., 925 µmoles g−1 h−1 and 190 µmoles g−1 h−1, respectively (RSD ≤ 11%, n = 4). The former composite, which affords an HER 15-fold higher in aqueous glucose than in neat water, provided H2 also with no metal co-catalyst (around 140 µmoles g−1 h−1), and it was reusable for at least three photoreactions. Encouraging results were also collected by explorative tests on raw starch solution (around 150 µmoles g−1 h−1).
Highlights
The search for new photocatalytic systems working under solar light for hydrogen production is increasingly triggering the interest of the scientific community
Glucose was selected as a biomass-derived sacrificial agent because in the wastewaters from food industry sugars are present at considerable amounts [4,5], and Pt was used as the reference metal co-catalyst because of its excellent properties for water reduction due to the large work function, resulting in a strong Schottky barrier effect [15,16]
The results collected highlight the importance to work under selected conditions to maximize the H2 yield while reducing the use of catalyst and co-catalyst
Summary
The search for new photocatalytic systems working under solar light for hydrogen production is increasingly triggering the interest of the scientific community. In the framework of novel photocatalysts, graphitic carbon nitride (g-C3 N4 ) has emerged in the last decade as one of the most promising material to run H2 photoproduction from water under visible light, due to cost-effective and easy synthesis, chemical stability, narrow band-gap and band potentials suitable to perform relevant redox reactions in aqueous solution [1,2]. Mainly fine chemicals have been used, as recently reviewed by Nasir et al [2], while just a few studies were undertaken in aqueous biomass solutions or directly in wastewaters [4,5,6]. Metal and non-metal doping, structural and morphological modifications, dye-sensitization, and combination with co-catalysts of different nature (e.g., carbon nanotubes, carbon dots, bimetallic deposition) have proved to be rewarding in terms of enhanced photocatalytic activity towards H2 generation from water in the presence of sacrificial agents [2,3].
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