Hydrothermal synthesis of advanced MoS2/Ni(OH)2 nanocomposite for efficient hydrogen evolution reaction and visible-light induced remediation of organic dyes

• MoS 2 /Ni(OH) 2 nanocomposite achieves a low overpotential of −0.232 V vs. RHE for 10 mA/cm 2 . • Remarkable photocatalytic degradation rates: 97 % for RhB in 14 min and 98 % for MB in 18 min. • Synergistic interactions at the interface of MoS 2 /Ni(OH) 2 enhance the charge mobility, active site exposure, and catalytic efficiency. • Excellent stability and durability, retaining performance after 1000 HER cycles and four dye degradation cycles. • Versatile dual-function catalyst for hydrogen evolution reaction and environmental applications, offering sustainable and cost-effective solutions. Building heterostructures is an established approach for developing highly effective electrocatalysts and photocatalysts. Two-dimensional molybdenum disulfide (MoS 2 ) nanoflowers stand out as promising catalysts in acidic media for hydrogen evolution reaction. In this study, MoS 2 /Ni(OH) 2 nanocomposite ( MoNi NC ), where Ni(OH) 2 nanosheets are successively decorated on MoS 2 surface, were synthesized for efficient hydrogen evolution reactions (HER). Compared to bare MoS 2 and Ni(OH) 2 , the MoNi NC demonstrated significantly improved HER activity in 0.5 M H 2 SO 4 as an acidic electrolyte, achieving a low onset potential of nearly −0.232 V vs. RHE to attain a current density of 10 mA cm −2 . Notably, the Tafel slope value was reduced by a factor of three (83 mV/dec), and the nanocomposite exhibited excellent stability compared to bare materials. The increased electrochemical performance of MoNi NC is due to the greater mobility of charge carriers at nanocomposite interface, as well as its improved surface area and active sites. Additionally, the MoNi NC showed significantly enhanced photocatalytic activity of Rhodamine B and Methylene Blue (RhB and MB) dyes compared to bare materials. In the visible light exposer for 14 and 18 min, the MoNi NC demonstrated an impressive rate of degradation, degrading RhB by 97 % and MB by 98 %. The increased degradation rate is likely due to the retardation of photoinduced charge recombination and the synergistic effects between the materials. A dual-function catalyst, that functions both as an electrocatalyst and photocatalyst, harnessing both electrical energy and light to drive chemical reactions efficiently. This study paves the way for designing efficient MoNi NCs for high renewable energy production and improved wastewater treatment.