Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using high-energy ball milling, followed by 0.5 and 1 wt% graphene loading. The corresponding vibrational and structural characterizations are consistent with the fabrication of a pure WS₂ structure for neat sampling and the presence of the graphene characteristic vibration modes in graphene@WS₂ compounds. Additional morphological and crystal structures were examined and confirmed by high-resolution electron microscopy. Subsequently, the investigations of the optical properties evidenced the high optical absorption (98%) and lower band gap (1.75 eV) for the graphene@WS₂ compared to the other samples, with good band-edge alignment to water-splitting reaction. In addition, the photoelectrochemical measurements revealed that the graphene@WS₂ (1 wt%) exhibits an excellent photocurrent density (95 μA/cm² at 1.23 V bias) compared with RHE and higher applied bias potential efficiency under standard simulated solar illumination AM1.5G. Precisely, graphene@WS₂ (1 wt%) exhibits 3.3 times higher performance compared to pristine WS₂ and higher charge transfer ability, as measured by electrical impedance spectroscopy, suggesting its potential use as an efficient photoanode for hydrogen evolution reaction.

Pure Fe ₂ O ₃ and Fe ₂ O ₃ doped with 2, 4, and 6 mass% of MnO ₂ (>99%) compacts annealed at 1473 K for 6 h were isothermally reduced with H ₂ at 1073–1373 K. The O ₂ weight loss resulted from the reduction of compacts was continuously recorded as a function of time using thermogravimetric analysis (TGA). High pressure mercury porosimeter, optical and scanning electron microscopes, X-ray phase analysis and vibrating sample magnetometer were used to characterise both the annealed and reduced samples. In MnO ₂ containing samples, manganese ferrite (MnFe ₂ O ₄ ) was identified. The rate of reduction of pure and doped compacts increased with temperature and decreased with the increase in MnO ₂ content. Unlike in pure compacts, the reduction of MnO ₂ containing samples was not completed and stopped at different extents depending on MnO ₂ (mass%). At initial reduction stages, the decrease in the rate was due to the presence of poorly reducible manganese ferrite (MnFe ₂ O ₄ ) phase which was partially reduced to iron manganese oxide (FeO _0.899 , MnO _0.101 ) at the final stages. The reduction mechanism was predicted from the correlation between the reduction kinetics and the structure of partially reduced samples at different temperatures. The reduction of pure and doped samples was controlled by a combined effect of interfacial chemical reaction and gaseous diffusion mechanism at their initial stages. At final stages, the interfacial chemical reaction was the rate controlling mechanism.