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Free keywords:
photocatalysis; single-atom catalysis; amination; amino acids; biomass derivatives
Abstract:
Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen-containing molecules. Here, we report the sustainable production of amino acids from biomass-derived hydroxy acids with high activity under visible-light irradiation and mild conditions, using atomic ruthenium-promoted cadmium sulfide (Ru<sub>1</sub>/CdS). On a metal basis, the optimized Ru<sub>1</sub>/CdS exhibits a maximal alanine formation rate of 26.0 mol<sub>Ala</<sub>·g<sub>Ru</sub><sup>-1</sup>·h<sup>-1</sup>, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru<sub>1</sub>/CdS to the facilitated charge separation and O-H bond dissociation of the α-hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique “double activation” mechanism of both the CH-OH and CH<sub>3</sub>-CH-OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.
