A Mo2C based electrocatalyst (Mo2C@SNC) was successfully synthesized with sulfur and nitrogen codoped carbon (SNC) as the matrix, which was derived from the shells of sunflower seeds. In the Mo2C/SNC, Mo2C particles that range in size from approximately 5 to 8 nm are evenly distributed in the sulfur and nitrogen codoped carbon matrix. Moreover, Mo2C/SNC has a large specific surface area with a mesoporous character. These particular structural features result in Mo2C@SNC having good electrocatalytic activity for hydrogen evolution reaction (HERs). To obtain 10 mA·cm–2 current in 1 M KOH, Mo2C@SNC only needs an overpotential as low as 60 mV. Mo2C@SNC also has outstanding durability and remains stable for over 2000 cycles. During a HER process, its hydrogen evolution rate reaches 90.2 μmol·h–1, with faradaic efficiency reaching almost 100%. Under acidic conditions, the advantages of Mo2C@SNC are obvious. In addition to electrocatalytic hydrogen evolution, Mo2C@SNC exhibits striking catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol. The conversion efficiency reaches almost 100% in 6 min with only a small amount of Mo2C@SNC used for the catalyst. In addition to 4-nitrophenol, Mo2C@SNC also affects methylene blue (MB), a common organic dye. We expect that Mo2C@SNC will become a new resource for H2 energy and will be a prospective material for water purification.

To obtain the photocatalyst composed by sulfur vacancies rich NiS and graphitic carbon nitride (g-C3N4), a simple method has been found for using coordination polymer as precursor. Based on this strategy, an effective composite photocatalyst, NiS@g-C3N4, is synthesized successfully through the calcination of a Ni2+ based coordination polymer with 2-mercapto-5-propylpyrimidine as ligand. In this photocatalyst, the NiS nanoparticles with small size disperse evenly in 2-mercapto-5-propylpyrimidine derived g-C3N4. Electron paramagnetic resonance (EPR) suggests there are a lot of sulfur vacancies in NiS@g-C3N4. NiS@g-C3N4 exhibits intensive adsorption in the near-infrared region, which endows NiS@g-C3N4 with promising photothermal effect. With a 980 nm laser as light source (0.44 W·cm–2), the aqueous dispersion of NiS@g-C3N4 exhibits a temperature elevation of 56.7 °C with photothermal conversion efficiency of 58.2%. Under irradiation of simulated solar light, without Pt co-catalyst, NiS@g-C3N4 possesses a promising photocatalytic H2 production rate, with the value 31.3 mmol·g–1·h–1. In five cycles of reactions for 30 h, the H2 production rate remains constant. The synergy between sulfur vacancy and photothermal effect of NiS play significant roles in the enhancement of H2 production property.

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