Nitrogen doped 1 T/2H mixed phase MoS₂/CuS heterostructure nanosheets for enhanced peroxidase activity

Heteroatom doping and phase engineering are effective ways to promote the catalytic activity of nanoenzymes. Nitrogen-doped 1 T/2H mixed phase MoS₂/CuS heterostructure nanosheets N-1 T/2H-MoS₂/CuS are prepared by a simple hydrothermal approach using polyoxometalate (POM)-based metal-organic frameworks (MOFs) (NENU-5) as a precursor and urea as nitrogen doping reagent. The XPS spectroscopy (XPS) and Raman spectrum of N-1 T/2H-MoS₂/CuS prove the successful N-doping. NENU-5 was used as the template to prepare 1 T/2H-MoS₂/CuS with high content of 1 T phase by optimizing the reaction time. The use of urea as nitrogen dopant added to 1 T/2H-MoS₂/CuS, resulted in N-1 T/2H-MoS₂/CuS with an increase in the content of the 1 T phase from 80 % to 84 % and higher number of defects. N-1 T/2H-MoS₂/CuS shows higher peroxidase activity than 1 T/2H-MoS₂/CuS and a catalytic efficiency (K_cat/K_m) for H₂O₂ twice as high as that of 1 T/2H-MoS₂/CuS. The enhanced catalytic activity has probably been attributed to several reasons: (i) the insertion of urea during the hydrothermal process in the S-Mo-S layer of MoS₂, causing an increase in the interlayer spacing and in 1 T phase content, (ii) the replacement of S atoms in MoS₂ by N atoms from the urea decomposition, resulting in more defects and more active sites. As far as we know, N-1 T/2H-MoS₂/CuS nanosheets have the lowest detection limit (0.16 µm) for the colorimetric detection of hydroquinone among molybdenum disulfide-based catalysts. This study affords a new approach for the fabrication of high-performance nanoenzyme catalysts.