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Nickel-iron sulfide has shown attractive activity in electrocatalytic oxygen evolution reaction (OER). However, the effects of low valence sulfur (S2−) and metal species on OER in binary nickel-iron sulfide have rarely been systematically studied. Works based on post-catalysis characterization have led to the assumption that the real active species are nickel-iron oxyhydroxide, and that nickel-iron sulfide acts only as a precatalyst. Therefore, to study the role of S, Ni, and Fe for the development of nickel-iron sulfide catalyst is of self-evident importance. Herein, a facile solvothermal method is used to synthesize acetylene black coated with nickel-iron sulfide nanosheets. Electrochemical tests show that the presence of low valence S species makes the catalyst have faster OER kinetics, larger active area, and intermediate active species adsorption area. Therefore, the present study reveals the enhancing effect of low valence sulfur species (S2−) on OER in binary nickel-iron sulfide. In situ Raman spectroscopy shows that the generation of γ-NiOOH intermediate is essential and Fe does not directly participate in the oxygen production. Density functional theory (DFT) calculation shows that Ni-OH deprotonation is a rate-determining step for both binary nickel-iron sulfide and nickel sulfide. The addition of Fe into NiSx lightly increases the charge transfer of Ni atom to O atom, which makes deprotonation easier and thereby improves the OER performance.

Molybdenum disulfide has received great attention as a promising non-noble catalyst for electro-catalyzed hydrogen evolution reaction. The active sites originated from the limited edge of crystalline molybdenum disulfide is the key to restrict its HER performance. To increase the active sites of molybdenum disulfide through the heteroatom doping with effective synthetic strategy has become the focus of activity improvement. Herein, a facile and efficient strategy was adopted to synthesize oxygen-doped molybdenum sulfide catalyst by utilizing thiourea and sodium molybdate as precursors. It was found that the number of active sites could be regulated by controlling the dosage ratio of thiourea to sodium molybdate. The doped oxygen and abundant S endows molybdenum sulfide a great deal of lattice disorder or defects, thus providing adequate active sites. When the optimized ratio of thiourea to sodium molybdate (40:1), the double layer value of oxygen-doped molybdenum sulfide reached 34.14 mF/cm2 (mass loading on glassy carbon electrode was 0.142 mg/cm2) which is considered to be proportional to the electrochemical active area. Raman spectroscopy and X-ray photoelectron spectroscopy confirmed the presence of Mo–O bond and bridging S22− bonds which endows molybdenum sulfide with a great deal of lattice disorder or defects, thus providing plentiful active sites.

The hydrosilylation of alkynes is a powerful process for producing vinylsilane compounds, which are synthetically versatile organosilicon reagents in organic chemistry. Herein, atomically dispersed Au anchored on g-C3N4 nanosheets is developed as a superior catalyst for the alkyne hydrosilylation reaction. The atomic Au species are in the +1 oxidative state coordinating with three nitrogen atoms observed via X-ray absorption fine structure (XAFS) characterization and analysis. Aromatic alkynes and aliphatic alkynes with various functional groups can effectively produce corresponding β-(E)-vinylsilane products with high conversion and selectivity. The atomically dispersed Au catalyst could be reused at least for five cycles without obvious decline in activity and selectivity. The unique structural and electronic characteristic of AuI–N3 sites are conducive to the successive activation of Si–H bonds, which boost the superior activity and selectivity of the single atom site Au in alkyne hydrosilylation.

Novel hexagonal α-cobalt hydroxide nanosheets are synthesized through a 2-methylimidazole-induced hydrolysis strategy with cetyltrimethylammonium bromide (CTAB) as a surfactant. The weak alkaline environment provides favorable conditions for the formation of metastable α-Co(OH)2, while the same raw material will produce β-Co(OH)2 when a strong alkali solution is used. CTAB plays a vital role not only in hexagonal oriented growth, but also in the formation of the hydrotalcite-like structure of α-Co(OH)2 with high crystallinity. The crystallinity of both α- and β-Co(OH)2 is very poor without CTAB as a surfactant. The Co in this Co(OH)2-x layer presents most of the CoII and a small part of the CoIII, and the interlayer nitrate anion balances the positive charge of the host layer. The redox function produced by the CoII and CoIII of α-Co(OH)2 together with the large layer spacing jointly promotes the electron and mass transfer. The use of hydrazine hydrate for transfer hydrogenation involves the transport of protons and electrons produced by decomposition, and the rapid transport is bound to be conducive to the reduction process. Nitro compounds with varieties of functional groups can be smoothly reduced to the corresponding amines with high selectivity, when α-Co(OH)2 was used as a catalyst under mild conditions.

Green waste compost (GWC) is a value-added product generated by the composting of urban green waste. Although GWC could potentially be used as a growth medium for soilless culture of plants, GWC alone has high salinity, high pH, and other undesirable physicochemical properties. In the current study, we therefore assessed how addition of vermiculite (VMT: 0, 3.5, and 7%) and humic acid (HA: 0, 0.5, and 1 g/100 g) affected the physicochemical properties of GWC and its use as a growth medium for cornflower (Centaurea cyanus L.). GWC modified by the combination of 3.5% VMT and 0.5 g/100 g HA had the best physicochemical properties (bulk density, porosity, water holding capacity, electrical conductivity, pH, and nutrient content) and resulted in the best growth of cornflower in terms of plant height, maximum root length, flower number, and biomass. The results therefore indicate that GWC modified by 3.5% VMT and 0.5 g/100 g HA powder is an excellent soilless growth medium.