Chemical synthesis of amino acids from renewable sources is an alternative route to the current processes based on fermentation. Here, we report visible-light-driven amination of biomass-derived α-hydroxyl acids and glucose into amino acids using NH3 at 50 °C. Ultrathin CdS nanosheets are identified as an efficient and stable catalyst, exhibiting an order of magnitude higher activity towards alanine production from lactic acid compared to commercial CdS as well as CdS nanoobjects bearing other morphologies. Its unique catalytic property is attributed mainly to the preferential formation of oxygen-centered radicals to promote α-hydroxyl acids conversion to α-keto acids, and partially to the poor H2 evolution which is an undesired side reaction. Encouragingly, a number of amino acids are prepared using the current protocol, and one-pot photocatalytic conversion of glucose to alanine is also achieved. This work offers an effective catalytic system for amino acid synthesis from biomass feedstocks under mild conditions.
Visible‐light‐responsive hierarchical Co9S8/ZnIn2S4 tubular heterostructures are fabricated by growing 2D ZnIn2S4 nanosheets on 1D hollow Co9S8 nanotubes. This design combines two photoresponsive sulfide semiconductors in a stable heterojunction with a hierarchical hollow tubular structure, improving visible‐light absorption, yielding a large surface area, exposing sufficient catalytically active sites, and promoting the separation and migration of photogenerated charges. The hierarchical nanotubes exhibit excellent photocatalytic H2 evolution and CrVI reduction efficiency. Under visible‐light illumination, the optimized Co9S8/ZnIn2S4 heterostructure provides a remarkable H2 generation rate of 9039 μmol h−1 g−1 without the use of any co‐catalysts and CrVI is completely reduced in 45 min. The Co9S8/ZnIn2S4 heterostructure is stable after multiple photocatalytic cycles.
Photocatalysis technology using solar energy for hydrogen (H2) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z‐scheme system with ZnIn2S4/BiVO4 heterojunction is proposed, which can precisely regulate redox centers at the ZnIn2S4/BiVO4 hetero‐interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn2S4/BiVO4 heterojunction exhibits excellent photocatalytic performance with a much higher H2‐evolution rate of 5.944 mmol g−1 h−1, which is about five times higher than that of pure ZnIn2S4. Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H2 production and a new strategy for the manufacture of remarkable photocatalytic materials.
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