Triple hierarchy and double synergies of NiFe/Co9S8/carbon cloth: a new and efficient electrocatalyst for the oxygen evolution reaction

Electrochemical water splitting requires an efficient water oxidation catalyst to accelerate the oxygen evolution reaction (OER). A triple hierarchy catalyst structure based on abundant transition metals in soil (Fe, Co, and Ni) was prepared via chemical bath deposition, followed by a hydrothermal and electrodeposition method for the high-efficiency OER. The obtained electrode consisted of a three-layer porous structure, with a carbon cloth (CC) substrate as the bottom layer, vertically aligned Co9S8 nanotubes as the intermediate layer, and NiFe hydroxide as the top layer, resulting in two synergistic effects between Co9S8 and CC, and NiFe and Co9S8. This layered structure contained no binder, which facilitated catalytic site exposure, enhanced electron transfer, and accelerated the dissipation of gases generated during the catalytic process. This triple hierarchy multimetal/carbon electrode exhibited remarkable OER activity in an alkaline medium with a small overpotential of 219 mV (vs. RHE) at 10 mA·cm-2 and low Tafel slope of 55 mV·dec-1. Furthermore, this triple hierarchy electrode was stable for up to 20 h. The prepared triple hierarchy polymetallic material can be considered to be among the most promising oxygen evolution catalysts.

Chemical grafting of Co9S8 onto C60 for hydrogen spillover and storage

Metal modified C₆₀ is considered to be a potential hydrogen storage medium due to its high theoretical capacity. Research interest is growing in various hybrid inorganic compounds-C₆₀. While the design and synthesis of a novel hybrid inorganic compound-C₆₀ is difficult to attain, it has been theorized that the atomic hydrogen could transfer from the inorganic compound to the adjacent C₆₀ surfaces via spillover and surface diffusion. Here, as a proof of concept experiment, we graft Co₉S₈ onto C₆₀via a facile high energy ball milling process. The Raman, XPS, XRD, TEM, HTEM and EELS measurements have been conducted to evaluate the composition and structure of the pizza-like hybrid material. In addition, the electrochemical measurements and calculated results demonstrate that the chemical "bridges" (C-S bonds) between these two materials enhance the binding strength and, hence, facilitate the hydriding reaction of C₆₀ during the hydrogen storage process. As a result, an increased hydrogen storage capacity of 4.03 wt% is achieved, along with a favorable cycling stability of ∼80% after 50 cycles. Excluding the direct hydrogen storage contribution from Co₉S₈ in the hybrid paper, the hydrogen storage ability of C₆₀ was enhanced by 5.9× through the hydriding reaction caused by the Co₉S₈ modifier. Based on these experimental measurements and theoretical calculations, the unique chemical structure reported here could potentially inspire other C₆₀-based advanced hybrids.

Counter electrodes in dye-sensitized solar cells

This article panoramically reviews the counter electrodes in dye-sensitized solar cells, which is of great significance for the development of photovoltaic and photoelectric devices.

Ultrathin Ni–Ni3Se2 nanosheets on graphene as a high-performance counter electrode for dye-sensitized solar cells

Ultrathin nanostructures of metal chalcogenides have exhibited excellent electrocatalytic activity due to the high percentage of surface atoms and many exposed interior atoms.

A facile one-pot hydrothermal synthesis of Co9S8/Ni3S2 nanoflakes for supercapacitor application

Co₉S₈/Ni₃S₂ nanoflakes have been successfully designed and constructed on nickel foam substrate via a simple one-pot hydrothermal synthesis and exhibit high performance as supercapacitor.