Ammonia-assisted MoS2/biomass-derived activated carbon electrocatalyst for alkaline hydrogen evolution

Biomass-derived activated carbon is a potentially low-cost support material for electrocatalytic hydrogen evolution reaction (HER). In this work, activated carbon derived from Cassia fistula pods (CFAC) was integrated with nanostructured MoS 2 at MoS 2 :CFAC weight ratios of 1:0.5, 1:1 and 1:2 through NH 4 OH-assisted solvothermal treatment. Structural and surface analyses indicate the dispersion of MoS 2 -containing species over the CFAC framework and the presence of nitrogen-containing surface functionalities. XPS also reveals surface Mo 6+ /Mo–O contributions, whereas XRD shows no distinct crystalline MoO 3 phase, indicating that the oxidized species are predominantly surface-localized or poorly ordered MoO x . Among the prepared materials, 1Mo–1C exhibited the best HER performance in 2 M KOH, requiring an overpotential of 74.5 mV to reach 10 mA cm −2 and displaying a Tafel slope of 156 mV dec −1 . It also retained approximately 88.6% of its initial current after 24 h, with post-stability FESEM showing retention of the interconnected composite framework. The performance of 1Mo–1C is instead associated with an optimum balance among electrochemically accessible area, available MoS 2 sites, nitrogen- and oxygen-containing surface functionalities, and MoS 2 –CFAC interfacial integration.