N-doped carbon-coated cobalt nanorod arrays supported on a titanium mesh as highly active electrocatalysts for the hydrogen evolution reaction

Development of effective technologies for clean and sustainable hydrogen energy has attracted great attention recently, as hydrogen is hailed as a promising energy source to reduce our dependence on fossil fuels and benet the environment by reducing the emissions of greenhouse and other toxic gases. To this end, an effective and promising approach is based on the electrolysis of water for hydrogen production. In these studies, advanced catalysts for the electrochemical hydrogen evolution reaction (HER) are required to achieve high current density at low overpotentials. Although platinum group metals are currently the electrocatalysts of choice that exhibit almost no overpotential, the scarcity and high costs of platinum severely limit its widespread applications in the HER, and it has remained a great challenge to develop highly active HER catalysts based on abundant materials (such as carbon and transition metals) with a low overpotential. As acidic solutions are preferred for water electrolysis to produce hydrogen, HER catalysts need to be acid-stable. Molybdenumand tungsten-based compounds are an exciting family of HER catalysts with a high performance, including MoS2, MoSe2, Mo2C, NiMoNx, MoP, and WS2, which exhibit excellent activity and robust stability in acidic electrolytes. A remarkable HER activity has also been observed with