Transition-metal-based NiCoS/C-dot nanoflower as a stable electrocatalyst for hydrogen evolution reaction

• Published in: International journal of hydrogen energy Vol. 44; no. 16; pp. 8214 - 8222
• Main Authors: Ali, Yousuf, Nguyen, Van-Toan, Nguyen, Ngoc-Anh, Shin, Sangho, Choi, Ho-Suk
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29.03.2019
• Subjects: Carbon dots; Hydrogen evolution reaction; Nanoflower; NiCo alloy; S-doping; Transition metal; S-doping; Nanoflower; Hydrogen evolution reaction; Transition metal; NiCo alloy; Carbon dots
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.01.297

Development of highly efficient electrocatalysts to produce hydrogen has been a significant topic over the past few decades. Currently, the platinum metal group shows the best catalytic performance for the hydrogen evolution reaction (HER), but the high cost and low abundance of these materials limit their wider application. Therefore, we synthesized transition-metal-based NiCoS along with carbon dots (C-dots) as a structure-directing agent by a hydrothermal method. We also synthesized sulfur-doped NiCo, where the sulfur enhances the conductivity of the catalysts. Herein, the synthesis temperatures were changed in the range from 120 to 240 °C. Among all, NiCoS synthesized at 150 °C shows the best HER performance capabilities. In more detail, NiCoS prepared at this temperature exhibits an onset potential of 96 mV and an overpotential of 232 mV. Especially, as-prepared NiCoS nanoflower subjects to long-term stability over 20 h at a current density of 10 mA/cm2, making it a promising low-cost candidate for hydrogen production. [Display omitted] •A carbon-dot (C-dot) assisted 3D nanoflower-like NiCoS electro-catalyst is synthesized.•The homogeneous growth of nano-sheets with void structure provides a large surface area.•Sulphur-doped NiCo synthesized at 150 °C exhibits the highest electro-catalytic activity.•The C-dot acts as a protective layer for NiCo and creates easy routes for electron transfers.