A new inorganic solid state electrocatalyst for the hydrogen evolution reaction (HER) is reported. Highly crystalline layered ternary sulfide copper-molybdenum-sulfide (Cu₂MoS₄) was prepared by a simple precipitation method from Cu^I and [MoS₄]²⁻ precursors. In aqueous solution and over a wide pH range (pH 0 to 7), this Cu₂MoS₄ showed very good catalytic activity for HER with an overvoltage requirement of only ca. 135 mV and an apparent exchange current density of 0.040 mA cm⁻² (Tafel slope of ca. 95 mV per decade was found irrespective of the pH value). This Cu₂MoS₄ catalyst was found to be stable during electrocatalytic hydrogen generation. Therefore, it represents an attractive alternative to platinum.

Photocorrosion, that causes rapid deactivation of Cu₂O photocatalysts, was addressed by incorporating this oxide in a composite with reduced graphene oxide which acts as an electron acceptor to extract photogenerated electrons from Cu₂O. Cu₂O–rGO composite engineering also allows enhancing significantly photocatalytic activities of Cu₂O for H₂ generation.

Nanowebs consisting of interwoven ZnFe₂O₄ nanofibers are synthesized by a simple electrospinning technique, to be employed as an environmentally friendly anode in lithium ion batteries. Effect of precursor viscosity on the growth mechanism of electrospun ZnFe₂O₄ nanofibers (ZFO-NF) and ZnFe₂O₄ nanorods (ZFO-NR) is studied by microscopy and diffraction techniques. Structural characterization by powder X-ray diffraction, FESEM and HRTEM studies evaluates the single phase nature of ZnFe₂O₄, which consists of 11(3) nm nanocrystals that self-agglomerate to form nanofibers after thermal treatment. FESEM micrographs depict the self-assembly of electrospun ZnFe₂O₄ nanofibers into intertwined porous nanowebs with a continuous framework. Benefitting from the one-dimensional functional nanostructured architecture, the application of electrospun nanowebs with ZnFe₂O₄ nanofiber (ZFO-NF) anodes in lithium ion batteries exhibits excellent cyclability and retains a reversible capacity of 733(10) mAh g⁻¹ up to 30 cycles at 60 mA g⁻¹ as compared to ZnFe₂O₄ nanorods (ZFO-NR) with a capacity of ∼200 mAh g⁻¹. In addition, the importance of providing electronic wiring during lithiation/delithiation, especially in prolonged cycling, is emphasized.

The potential of water (photo)electrolysis technology to provide hydrogen as a fuel on a large scale depends on how viable electrocatalysts for the water oxidation reaction (WOR) and the hydrogen evolution reaction (HER) are and whether they can be constructed from elements which are abundant in the Earth's crust. Here we show that ternary sulfides of cobalt–tungsten and nickel–tungsten (MWS_x where M is Co or Ni) are efficient and robust electrocatalysts for the HER in water over a wide pH range. These novel ternary sulfides were readily grown on a conducting electrode surface by employing a scalable electrodeposition process from aqueous solutions of [M(WS₄)₂]²⁻. In terms of HER activity, the MWS_x catalysts represent attractive alternatives to platinum. Moreover, we show that the HER activity is governed by the nature of the metal M within M–S–W heterobimetallic sulfide centres, located in the WS₂-like layered structure of MWS_x. Our work provides structural and mechanistic keys to understand how HER activity is promoted in previously described nickel and cobalt-doped molybdenum and tungsten sulfide materials.