Designing and developing active, cost-effective and stable electrocatalysts for hydrogen evolution reaction (HER) are still an ongoing challenge. Herein, we report the synthesis of binary transition metal phosphide (CoxFe1-xP) nanocubes with different Co and Fe ratios through a phosphidation process using metal-organic frameworks (MOFs) as templates. MOF templates contribute well-defined nanocube architectural features after phosphidation, while a suitable phosphidation temperature could allow formation of a crystal structure and maintain the well-defined structure. The incorporation of a binary transition metal results in redistribution of the valence electrons in CoxFe1-xP. The changes imply anionic states of the P and Fe atoms, which act as active sites and thus have stronger electron-donating ability. When CoxFe1-xP nanocubes are employed as electrocatalysts, these characteristic features facilitate the performance of HER. Remarkably, Co0.59Fe0.41P nanocubes prepared at 450 °C afford a current density of 10 mA cm(-2) at a low overpotential of 72 mV in acidic conditions and 92 mV in alkaline conditions. Co0.59Fe0.41P nanocubes also exhibit a small Tafel slope of 52 mV decade(-1) in acidic conditions and 72 mV decade(-1) in alkaline conditions. Moreover, Co0.59Fe0.41P nanocubes show good stability in both acidic and alkaline conditions. Our method produces the highly active HER catalyst based on binary transition metal MOF templates, providing a new avenue for designing excellent electrocatalysts.

A synthetic route to FeP-GS hybrid sheets that show good stability and high electrocatalytic activity for hydrogen evolution reaction is reported. The materials are prepared via thermal phosphidation of pre-synthesized Fe3O4-GS hybrid sheets.

Fluorescent carbon dots (C-dots) are prepared directly via a simple hydrothermal method using bovine serum albumin (BSA) as a carbon source in the presence of surface passivation reagents. The obtained C-dots have low cytotoxicity and good biocompatibility, demonstrating that their features are good for application in cell imaging.Fluorescent semiconductor quantum dots (QDs) have attracted much attention over the past two decades for a variety of purposes and applications, especially in optical imaging agents, electronics, biotechnology, sensors and catalysis due to their high quantum yield and size-tunable fluorescence color. [1][2][3][4][5][6][7] Unfortunately, QDs are commonly synthesized using toxic heavy metals (e.g., cadmium, lead), 8 which limit their widespread use and in vivo biological applications because of potential environmental hazards and long term toxicity concerns. Therefore, considerable efforts have been made to search for environmentally-friendly and low toxicity fluorescent nanomaterials.Recently, fluorescent carbon dots (C-dots) have emerged as the most alternative fluorescent probes to replace traditional QDs. Compared with QDs, C-dots are highly attractive for bioimaging, 9,10 photocatalysis, 11 and light emitting devices 12 because of their chemical stability, biocompatibility, low toxicity and reasonable photoluminescence. 13,14 The C-dots are generally small oxygenous carbon nanoparticles of near spherical geometry with sizes below 10 nm, and they inherently fluoresce in visible upon light excitation. Since they were discovered by Xu et al. while purifying single-walled carbon nanotubes derived from arcdischarge soot, C-dots have been produced via various methods. So far, C-dots can be prepared by two main approaches: top-down and bottom-up routes. 15 Top-down methods consist of laser ablation or electrochemical oxidation of graphite, 16,17 electrochemical treatment of multiwalled carbon nanotubes, 18,19 and chemical oxidation of commercially activated carbon etc. 20 Bottom-up methods consist of microwave pyrolysis of saccharides, 21,22 combustion soot of candles, 23 supported synthetic methods, 24,25 chemical or thermal oxidation of suitable precursors, 26,27 and RSC Advances

A thorough understanding of the effect of N doping on the oxygen evolution reaction (OER) is greatly significant for constructing next-generation electrocatalysts with an optimal configuration and high efficiency for the fuel cell. Herein, we reported the synthesis of N-doped CoS2 through a facile method using ammonium hydroxide as the N source, the subjection of N-doped CoS2 as efficient electrocatalysts for OER, and the identification of intrinsic activities by exploring the composition and electronic configurations and their correlations with the electrochemical performance. The DFT studies evidenced that N doping could alter the electronic density of the adjacent Co atoms and thus form well-defined electronic configurations for adsorption of intermediates. Specifically, the N-enriched CoS2 afford a small overpotential of 240 mV at the current density of 10 mA cm–2 and long-term durability, endowing these N-doped materials to be ideal (but not limited to) OER electrocatalysts.

promising sustainable processes. [ 6 ] Pt and Pt-based materials are regarded as the most promising electrocatalysts for the HER due to their high electrocatalytic activity, versatility, high conductivity, and chemical inertness, whereas the practical commercialization is hindered by their high cost and scarcity. [ 7 ] The exploration of Earth-abundant HER electrocatalysts has gained great enthusiasm, including metal carbides, [ 8 ] metal sulfi des, [ 9 ] metal selenides, [ 10 ] metal phosphides, [ 11 ] graphitic carbon nitride, [ 12 ] and so on. The other half-reaction of the water splitting, OER, is considered to be the rate-limiting process of water splitting, which sustains sluggish kinetics that derive from four electron/ proton-removal steps, each with different energy barriers. [ 13 ] Ru and Ir oxides are the most effi cient OER catalysts, although their practical applications are hindered by their high cost. [ 14 ] Developing and designing high-performance nonprecious electrocatalysts is highly desirable for the OER. [ 15 ] Currently, most effort is focused on the development of new electrocatalysts that could overcome the intrinsic activation barriers of the HER and OER. The gas evolution on the electrocatalysts is also important, but was not yet optimized. The rapid evolution of oxygen or hydrogen bubbles from the electrocatalysts might destroy them, resulting in performance degradation in long-term application. On the other hand, the bubbles attached to the surface of electrocatalysts would reduce the active area of electrode and block electrolyte diffusion, and inhibit further electrochemical reaction. [ 16 ] In this scenario, an electrode that is superhydrophilic in air and superaerophobic under water would be ideal for the HER and the OER. A superhydrophilic surface has an apparent contact angle (CA) with water of less than 5 or 10°, whereas a superaerophobic surface usually has a gas bubble CA of larger than 150°. [ 17 ] Sun and co-workers prepared underwater superaerophobic MoS 2 and pine-shaped Pt nanostructure electrodes, which could easily drive off hydrogen bubbles and achieved much higher current density than the aerophobic products. [ 18 ] Yan and co-workers prepared hydrophilic N-S co-doped Mo 2 C nanosheet electrodes, which showed an increase in the number of electrolyte-electrode contact points and resulted in enhanced HER performance. [ 19 ] However, to our knowledge, a simultaneously superhydrophilic and Bifunctional, binder-free, and non-precious-metal electrocatalysts with superwetting properties are of great signifi cance for high-performance oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). Herein, the fabrication of copper phosphide (Cu 3 P) microsheets through the phosphidation of CuCl microsheets deposited onto nickel foam, and the effective catalytic activity of the Cu 3 P microsheets in the HER and OER is demonstrated. Due to their hierarchical structure, the Cu 3 P microsheets are superhydrophilic and superaerophobic. A well-defi ned superhydroph...

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A facile two step process was developed for the synthesis of porous Co3O4 nanorods-reduced graphene oxide (PCNG) hybrid materials based on the hydrothermal treatment cobalt acetate tetrahydrate and graphene oxide in a glycerol-water mixed solvent, followed by annealing the intermediate of reduced graphene oxide-supported Co(CO3)0.5(OH)·0.11H2O nanorods in a N2 atmosphere. The morphology and microstructure of the composites were examined by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. It is shown that the obtained PCNG have intrinsic peroxidase-like activity. The PCNG are utilized for the catalytic degradation of methylene blue. The good catalytic performance of the composites could be attributed to the synergy between the functions of porous Co3O4 nanorods and reduced graphene oxide.

A defect‐rich CoP/nitrogen‐doped carbon composite is reported for the first time derived from ZIF‐67 by means of low‐temperature phosphidation process. As a hydrogen evolution reaction electrocatalyst, the obtained CoP‐N‐C has high HER activity and good stability with a low onset overpotential of 31 mV, a small Tafel slope of 42 mV dec−1, a large exchange current density of 1.6×10−1 mA cm−2, and a 10 mA cm−2 current density at overpotential 91 mV.