  The hybrid nanostructures of nitrogen doped carbon materials and nonprecious
transition metals are among the most promising electrocatalysts to replace
noble metal catalysts for renewable energy applications. However, the
fundamental principles governing the catalytic activity of such hybrid
materials remain elusive. Herein, we systematically explore the
electrocatalytic properties of transition metals, transition metal oxides and
carbides substrates covered by nitrogen-doped graphitic sheets for hydrogen
evolution reaction (HER). Our first-principles calculations show that the
graphitic sheet is prominently activated by the nitrogen doping and the
coordinate bond with metal (compound) substrate through intralayer and
interlayer charge transfer. Such hybrid materials can provide optimal binding
capability for HER catalysis with Tafel barrier down to 1.0 eV. The HER
activity can be correlated to the C pz band center, which is in turn governed
by the electronic coupling strength between the graphitic sheet and metal
substrate, thus paving a way to rational design of graphitic carbon/transition
metal hybrid electrocatalysts of high performance.
