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Molybdenum carbide materials have demonstrated remarkable potential in catalyzing the hydrogen evolution reaction (HER). However, further modulation of their performance through simultaneously engineering the size and surface crystal facets remains challenging. Herein, we report the successful fabrication of N-doped carbon-supported monodisperse Mo 2 C nanoparticles with a size of ∼2.06 nm, exhibiting co-exposed (101)/(102) facets-heterojunction, derived from annealing glycine and ammonium molybdate tetrahydrate. The optimized Mo 2 C/NC-Amt catalyst exhibits a low overpotentials of 128 mV to achieve the current density of 10 mA cm−2 and a small Tafel slope of 72 mV dec−1 under alkaline solution. By changing the molybdate precursor, the phase and crystal facet composition of molybdenum carbide can be effectively tuned, which provides a good platform for studying their structure-activity in HER. The theoretical calculations reveal the synergistic effect of (101)/(102) facets-heterojunction accelerates electron transfer and regulates the d band center of Mo 2 C, reducing the reaction barriers of intermediates in the HER process, thus significantly boosting reaction activity. This work proposes a novel insight into the rational fabrication of efficient HER catalysts through facet engineering toward heterojunction construction under the 2.5 nm region. [Display omitted] • Monodisperse Mo 2 C nanoparticles (∼2.06 nm) on N-doped carbon are synthesized. • The formed surface heterojunction involves (101) and (102) facets of Mo 2 C. • DFT calculations reveal the synergistic mechanisms of the facet heterojunctions. • The optimized catalyst presents distinguished HER performance in 1 M KOH. [ABSTRACT FROM AUTHOR]

We report on a highly active and stable FeNC non noble metal catalyst for the oxygen reduction reaction in alkaline solution. To prepare the FeNC non noble metal catalyst graphitic carbon nitride (g-C 3 N 4 ) and FeCl 3 are used as nitrogen and iron source, respectively. Iron is proved essential for the high catalyst activity. The best catalyst shows similar onset potential with commercial Pt/C catalyst in alkaline solution. The paper reveals whether the Fe 4 N composite is active in the oxygen reduction reaction. The as prepared catalysts show excellent stability with no change in activity after 10,000 cycles of acceleration test. The stability is explained by the protection effect of layers of graphitic carbon on the surface. The as prepared catalyst catalyzes the ORR via a four electron process with similar kinetics to that of Pt/C. The high activity and stability make this catalyst good candidate in alkaline fuel cell and metal air batteries. [ABSTRACT FROM AUTHOR]

Nitrogen doped carbon material works as non-noble-metal catalyst for the oxygen reduction reaction. In this work the doping effect on two different carbon material by two different nitrogen sources is studied. The carbon material studied is self-prepared carbon ribbon with higher graphitization degree compared with commercial Vulcan XC72 carbon powder. NH 3 and glycine are used as nitrogen sources which produce nitrogen containing functionalities after high temperature pyrolysis. NH 3 doping of carbon ribbon has no positive effect on the ORR activity, while an obvious increase in the activity is found for the glycine doped carbon ribbon. The NH 3 and glycine doped Vulcan carbon show similar activities which are better than undoped Vulcan carbon. The difference is explained by graphitization degree, nitrogen content and type of nitrogen containing functionalities. [ABSTRACT FROM AUTHOR]