Four-in-one strategy to boost the performance of 3-dimensional MoS₂ nanostructures for industrial effluent treatment and hydrogen evolution reactions

Two-dimensional (2D) molybdenum disulfide (MoS₂) has gained enormous attention as a photocatalytic material due to its extraordinary optical, electrical, and chemical properties which are highly tunable by engineered control of its 2D layers orientation. However, high carrier recombination rates in pristine MoS₂ nanostructures hinder their practical applications as an efficient catalyst. There is an upsurge of research on developing new strategies to improving its photocatalytic actions for environmental remediation. One approach is to design MoS₂ nanostructures with vertically aligned layer-structures or cross-linking 3-dimensional flower-like morphologies, which exhibit ultrahigh-density 2D edge sites that offer tremendous chemical reactivity. Another challenge is to obtain its highly active metallic 1 T phase by functional design of intrinsic structures without sacrificing its ambient stability. Herein, we reported highly active and mix-phased 1 T/2 H MoS₂ nanostructures through elegant synthesis management. By regulating reaction kinetics with the assimilation of NH₄⁺ ions and water molecules, tunable surface morphology from nano wrinkles to nanoflowers was achieved. The morphology regulations induced modifications in the surface areas of final products which were calculated as 64.3 m²g⁻¹_, 114.3 m²g⁻¹, and 219.7 m²g⁻¹, respectively. Moreover, the bandgaps were significantly lowered from 2.13 eV to 1.93 eV and 1.85 eV. This four-in-one strategy efficiently boosted photodegradation of organic pollutants up to 94% in less than 20 min with excellent cyclic reproducibility for seven cycles. In addition, exceptional hydrogen evolution reaction (HER) performance with a very low overpotential of 145 mV and Tafel slope of 81.4 mV/dec was recorded. The results obtained in this work demonstrated excellent suitability of these materials as catalysts in environment related applications such as organic dye removal and for efficient hydrogen production.