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[Display omitted] • Mn doping strategy is proposed to enhance the HER activity of MoP for the first time. • Mn doping can optimize the electronic configuration of MoP. • Mn doped MoP is demonstrated as a highly efficient HER catalyst. • The 0.05Mn-MoP exhibits the best HER activity. Rational design of robust and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is crucial for the development of energy conversion technologies. Molybdenum phosphide (MoP) has displayed excellent HER activities and triggered substantial interests as a promising water splitting electrocatalyst. In this work, a Mn doping strategy is proposed to improve the HER performances of MoP for the first time as well as the construction of novel porous interconnected structures. And the effect of doping contents and corresponding improvement mechanism are also discussed. It is found that the obtained 0.05Mn-MoP catalyst with porous interconnected nanosheets (NSs) presents the best HER properties as well as outstanding durability. The porous interconnected structures offer more exposed active sites, and the Mn doping optimizes the electronic configuration of MoP, leading to lower charge transfer resistance and higher intrinsic activity. This work provides a facile method to construct porous structures and demonstrate the effective strategy of Mn doping for the enhancement of MoP for the HER. [ABSTRACT FROM AUTHOR]

• Highly porous Mo 2 C/C is prepared using the N, K co-activated biochar as carbon source and matrix. • The obtained porous Mo 2 C/C shows a large specific surface area with nitrogen doping. • The porous architecture with a large specific surface area can afford abundant catalytic sites. • The interconnected N-rich carbon matrix provides efficient electron transfer pathways for HER. Molybdenum carbide (Mo 2 C) has offered great promise to serve as a platinum substitute towards efficient hydrogen evolution reaction (HER). However, both the lack of exposed catalytic sites and strong Mo–H binding strength will strongly hinder the HER process for Mo 2 C-based electrocatalysts. Herein, a scalable strategy is proposed for the preparation of highly porous Mo 2 C/C electrocatalysts with a specific surface area up to 611 m2 g−1 as well as uniform nitrogen doping derived from N, K co-activated biochar (NKAB). And the porous architecture with a large specific surface area can afford abundant catalytic sites. Additionally, both the Mo 2 C and carbon matrix are doped with nitrogen effectively, which can optimize the hydrogen adsorption free energy of Mo 2 C/C electrocatalysts associated with a higher intrinsic activity. As a result, the active site density and intrinsic activity of Mo 2 C/NKAB have been promoted simultaneously on account of the high specific surface area and nitrogen doping. Furthermore, the interconnected N-rich carbon matrix provides efficient electron transfer pathways for superior HER kinetics. Ultimately, the overall HER performances of Mo 2 C/NKAB can be significantly enhanced. [ABSTRACT FROM AUTHOR]