Spent Zinc–Carbon\nBattery-Derived Carbon Nanoparticles\nCoupled with Transition Metal Dichalcogenides for Enhanced pH-Universal\nHydrogen Evolution Reaction

Utilizing highly effective waste-into-value electrocatalysts\nfor\nthe hydrogen evolution reaction (HER) opens a sustainable route to\neconomically beneficial and environmentally friendly hydrogen production.\nA simple strategy for reusing spent batteries involves enhancing HER\nperformance by preparing electrocatalysts of the carbon anode in spent\nzinc–carbon batteries and transition metal dichalcogenide (TMDs)\nmaterials. In this study, carbon nanoparticles (C<sub>NPs</sub>) are\nincorporated into the basal planes of MoS<sub>2</sub> and WS<sub>2</sub> using a simple ultrasonication method. C<sub>NPs</sub>@TMDs (C<sub>NPs</sub>@WS<sub>2</sub> and C<sub>NPs</sub>@MoS<sub>2</sub>) with\nfewer-layer structures and enhanced exposed active sites show promising\ncatalytic activity for pH-universal HER. In acid, C<sub>NPs</sub>@WS<sub>2</sub> and C<sub>NPs</sub>@MoS<sub>2</sub> exhibit overpotentials\nof 0.34 and 0.42 V at 10 mA cm<sup>–2</sup>, with Tafel slopes\nof 0.139 V dec<sup>–1</sup> and 0.145 V dec<sup>–1</sup>, respectively. The enhanced HER performance of C<sub>NPs</sub>@TMDs\noriginates from their improved electrical conductivity and higher\nelectrochemically active surface area. Alongside experimental results,\ndensity function theory (DFT) calculations reveal that incorporating\ncarbon atoms on the TMD surface can efficiently tune the electronic\nproperties of MoS<sub>2</sub> and WS<sub>2</sub> monolayers from semiconductor\nto semimetal and considerably reduces the hydrogen adsorption Gibbs\nfree energies. These results indicate that highly effective HER catalysts\nwith enhanced catalytic activity in universal pH media are fabricated\nvia an economical and facile method, holding promise for practical\napplications and paving the way for battery recycling.