We report a facile synthetic protocol to prepare mesoporous FeS without the aid of hard template as an electrocatalyst for the hydrogen evolution reaction (HER). The mesoporous FeS materials with high surface area were successfully prepared by a sol-gel method following a sulfurization treatment in an HS atmosphere. A remarkable HER catalytic performance was achieved with a low overpotential of 96 mV at a current density of 10 mA·cm and a Tafel slope of 78 mV per decade under alkaline conditions (pH 13). The theoretical calculations indicate that the excellent catalytic activity of mesoporous FeS is attributed to the exposed (210) facets. The mesoporous FeS material might be a promising alternative to the Pt-based electrocatalysts for water splitting.

The electrolysis of water provides a powerful pathway for the storage and conversion of clean and renewable energy. Therefore, the development of earth-abundant, inexpensive, highly efficient electrocatalysts contributes a great deal to the overall efficiency of a water electrolytic system. Here, inspired by the low charge transfer resistance of mixed-valence cations, the favorable H atom binding energy of cobalt, and high electrical conductivity of graphene, we report a facile synthesis strategy to synthesize a spinel ternary oxide material consisting of nickel, manganese, and cobalt supported on reduced graphene oxide (rGO/NMC) with further conversion into a spinel ternary sulfide via a gaseous sulfurization protocol. The rGO/NMC-312 oxide material is found to be an efficient OER electrocatalyst with an overpotential as low as 320 mV for a current density of 10 mA cm −2 , which is comparable to that of the state of the art OER catalysts. In addition, when used as HER electrocatalysts, the as-converted rGO/ NMC-312 sulfide materials exhibit a low overpotential of 151 mV to reach a current density of 10 mA cm −2 , a small Tafel slope of 52 mV/decade, and a remarkable long-term stability. Impressively, a voltage of 1.56 V is required to achieve a current density of 20 mA cm −2 in an alkaline medium at room temperature by applying rGO/NMC-312 oxide and sulfide as an alkaline water electrolysis anode and cathode, respectively. Our work offers a strategy to apply spinel ternary oxides and sulfides as electrocatalysts in water electrolysis.

Three different modification (doping, solvent free, and impregnation) methods were used to obtain a series of mesoporous Cu-TiO 2 materials with various copper loading amounts (0 to 15 mol %). The influence of the modification procedure on the physico-chemical properties was characterized by PXRD, N 2 sorption, SEM, EDX elemental mapping, and XPS techniques. The presence of copper species have been detected either in the TiO 2 lattice as Cu + (via doping methods) or on the surface of TiO 2 as CuO species (via solvent free and impregnation methods). With the modification of Cu, the surface area of mesoporous Cu-TiO 2 materials can be increased up to 128 m 2 /g. The catalytic activities of Cu-TiO 2 materials were investigated using the alkyne-alkyne homocoupling reaction with air as the sole oxidant under mild reaction conditions without any additives. The doped Cu-TiO 2 materials show the highest catalytic activity (1,4-diphenyl-1,3-butadiyne yields > 99%). The different catalytic mechanisms, active sites, and structure-property relationships of all the catalysts are discussed. Definitive features affecting the catalytic performance of the obtained Cu-TiO 2 materials are the loading amounts and the states of Cu, surface area, and pore size distributions. Reusability tests were conducted on the collected sample without washing, and 74% yield was achieved even after three cycles.

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