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Herein, we have reported an easily synthesized CoS2/Ni3S2/CoNiOx water oxidation catalyst with excellent catalytic activity and superior durability. The as-prepared catalyst required overpotential (η) as low as 256 mV to exhibit a current density of 10 mA cm−2 in 1.0 M KOH. Remarkably, it sustained a current density of 1 A cm−2 for one week in 30% KOH solution with only 25 mV increment of η. Thus, it is a hopeful candidate as a highly-effective water oxidation electrode in practical applications. [ABSTRACT FROM AUTHOR]

MoS2-decorated C3N4 (C3N4/MoS2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension (2D) C3N4 and MoS2 nanosheets. The effects of MoS2 content on the light absorption, charge transfer and photocatalytic activity of the hybrid samples were investigated. Characterization results show that MoS2 nanosheets are well anchored on the face of C3N4 nanosheets and the composites have well dispersed layered morphology. After loading with MoS2, the light absorption of composites was much improved, especially in visible-light region. The photocatalytic activities of C3N4/MoS2 samples were evaluated based on the H2 evolution under visible light irradiation (λ > 400 nm). When the loading amount of MoS2 was increased to 5 wt%, the highest H2 evolution rate (274 μmol·g-1·h-1) was obtained. Compared with samples obtained from direct impregnation method, sonication pretreatment is favorable for the formation of 2D layered heterojuctions and thus improve the photocatalytic activity. Slightly deactivation of C3N4/MoS2 composites could be observed when recycled due to the mild photocorrosion of MoS2. Based on the band alignments of C3N4 and MoS2, a possible photocatalytic mechanism was discussed, where MoS2 could efficiently promote the separation of the photogenerated carriers of C3N4. [ABSTRACT FROM AUTHOR]

Abstract: A simple and low‐cost fabrication method is needed to obtain effective and robust heterogeneous catalysts for the oxygen evolution reaction (OER). In this study, an electrocatalyst FeNiOxHy with a hierarchical structure is synthesized on nickel foam by a simple fabrication method through anion exchange from a metal phosphate to a metal hydroxide. The as‐fabricated FeNiOxHy electrode requires overpotentials of 206 and 234 mV to deliver current densities of 10 and 50 mA cm−2, respectively. The catalytic performance of FeNiOxHy is superior to that of most previously reported FeNi‐based catalysts, including NiFe layered double hydroxide. The catalyst also shows good long‐term durability at a current density of 50 mA cm−2 over 50 h with no activity decay under 1  m KOH. By comparison to the directly electrodeposited FeNi hydroxide in morphology and electrochemical properties, the improved activity of the catalyst could be mainly attributed to an enhancement of its intrinsic activity, which was caused by the anion exchange of phosphate to (oxy)hydroxide. Further studies by cyclic voltammetry indicated a stronger interaction between Ni and Fe from the negative shift of the oxidation peak of Ni2+/Ni3+ in comparison with reported FeNiOxHy, which promoted the generation of active Ni3+ species more easily. This work may provide a new approach to the simple preparation of effective and robust OER catalysts by anion exchange. [ABSTRACT FROM AUTHOR]

Sulfur doped carbon nitride materials (CNS) were prepared from solvothermal method at low temperature, using thiocyanuric acid as one of the precursors. XRD, FTIR, SEM and XPS technologies were carried out to characterize the catalysts. The photocatalytic reduction properties of CNS were tested by Cr(VI) reduction and H2 production from water splitting. Results showed that sulfur substituted crystal nitrogen in the carbon nitride molecular and formed C--S bonds. With the increasing time of polymerization, the content of sulfur in the products increased. The catalysts showed remarkable visible light absorbance, and the optical absorption band edges red shifted up to about 700 nm with the increasing time of polymerization. Compared to the carbon nitride synthesized from direct calcination, CNS possessed much enhanced photocatalytic reduction activity of Cr(VI) under visible light irradiation. In addition, CNS catalysts had obvious H2 production properties from water splitting. Mechanism analysis showed that photo-generated electrons and ⋅ O2v- were major active species during photocatalytic reduction of Cr(Vi) over CNS catalysts. [ABSTRACT FROM AUTHOR]