2D/2D CdS/1T-MoS2 heterojunctions with abundant interfacial sulfur vacancies for high-efficient photocatalytic amino acid synthesis from bio-based feedstocks

Photocatalytic amino acid synthesis from biomass is a promising and renewable method, yet the synthesis efficiency remains suboptimal. Here, we report a novel strategy for synthesizing 2D/2D CdS/1T-MoS 2 heterojunctions by leveraging 1T-phase MoS 2 with distorted octahedral coordination and sulfur-rich edges to promote the formation of large contact areas and abundant interfacial sulfur vacancies in combination with CdS. CdS/1T-MoS 2 displays exceptional photocatalytic performance for amination of biomass-derived α-hydroxy acids to α-amino acids, achieving an alanine formation rate of 23.3   mmol·g -1 ·h -1 from lactic acid, which is 4.4 and 1.6 times higher than those of CdS and CdS/2H-MoS 2 , respectively. Detailed characterizations reveal that CdS/1T-MoS 2 possesses abundant interfacial sulfur vacancies at the 2D/2D heterojunction interface compared to CdS and CdS/2H-MoS 2 . These vacancies create numerous Lewis acids sites, significantly enhancing the adsorption and activation of hydroxyl groups in lactic acid, thereby promoting the dehydrogenation step. Moreover, CdS/1T-MoS 2 facilitates the condensation of pyruvic acid with ammonia and promotes the desorption of alanine from the catalyst surface, effectively improving the reductive amination step. Additionally, CdS/1T-MoS 2 exhibits superior charge carrier separation and migration efficiency, further boosting its photocatalytic amination activity. This study provides a novel strategy for synthesizing 2D/2D heterojunctions with abundant interfacial vacancies for efficient photocatalytic biomass valorization.