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• A dual-site doping strategy is developed for efficient bifunctional catalysts. • Both optimized electronic structure and increased active species were achieved. • The N,Ni-Co 2 P@TC shows extraordinary stability at high current density. • Dual-site doped N,Ni-Co 2 P@TC exhibits enhanced catalytic activities for HER and OER. The exploration of novel, super-potent and low-cost electrocatalysts for water splitting has always been the kernel in the field of renewable sources. Herein, exfoliated Ti 3 C 2 T x MXenes work as a substrate to vertically grow polypore N,Ni-Co2P nanoarrays (N,Ni-Co2P@TC) through an in situ interface-growth strategy and subsequent phosphorization and nitridation. The well-defined heterointerfaces with positive and negative ions co-modulation as coupled hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysts for efficient overall water splitting are investigated, which possesses excellent durability even at a large current density (±500 mA cm-2). For HER, suitable H 2 O* and H* absorption energies and accelerated electronic transmission make N,Ni-Co2P@TC display a low overpotential of 27 mV at -10 mA cm-2 and Tafel slope of 38 mV dec‑1 in 1 mol/L KOH. For OER, the synergy of N,Ni-Co2P@TC with self-reconfiguration can give enhanced activity with a low overpotential of 232 mV at 10 mA cm-2 and a Tafel slope of 57 mV dec‑1. Additionally, the excellent bifunctional activity allows easily combining for efficient overall water splitting with a low driving voltage (1.51 V) at 10 mA cm-2, and the electrolyzer can be driven by a 1.5 V AAA battery. [ABSTRACT FROM AUTHOR]

• The ZIF-67-derived Co 2 P was anchored on bimetallic Ti 2 VC 2 T x MXene and formed heterostructures for the first time. • The self-doped carbon and nitrogen modulate the electronic structures and enhance the adsorption of oxygen-containing intermediates of the catalyst. • It has an ultrahigh-specific surface area (1174.2 m2 g–1) and more active sites. • It has excellent electrochemical performance with an ultralow tafel slope of 28.18 mV dec–1 for OER. Oxygen evolution reaction (OER) is central to technologies such as electrochemical water splitting, and developing efficient and low-cost non-precious metal electrocatalysts for OER is of great significance to reducing cell voltage and developing hydrogen production by electrochemical water splitting. Herein, we prepared a carbon, nitrogen co-doped porous Co 2 P derived from the metal-organic framework (ZIF-67), which is anchored on bimetallic MXene nanosheets (named MX@MOF-Co 2 P). It was used as the OER catalyst and exhibited great electrocatalytic performance with very small overpotentials (246 mV at 10 mA–2 and 407 mV at 200 mA cm–2) as well as ultralow Tafel slope (28.18 mV dec–1). Combining characterizations and theoretical calculations, it was found that the remarkable performance was from follows: the obtained MX@MOF-Co 2 P inherited the porous structure of the pristine MOF with a large number of open active sites; carbon and nitrogen doping also modulated the electronic structure of the active center; the synergistic effect between cobalt phosphide and MXenes booted the electronic transfer. This work represents a promising strategy for the development of non-precious metal catalysts derived from metal-organic frameworks to achieve efficient energy conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • A kind of MoS 2 /Co 9 S 8 /MoC heterostructure connected with nitrogen-doped carbon nanotubes was successfully prepared. • It has excellent hydrogen evolution performance. • Its excellent activity is attributed to the introduction of Co and N atoms and the formation of carbon nanotubes. High-performance multifunctional materials for water splitting driven by low voltage are crucial for hydrogen evolution reaction (HER), but developing such materials is challenging. Herein, a simple strategy was designed to build a MoS 2 /Co 9 S 8 /MoC@CNT-N (MCM@CNT-N) heterostructure with a large number of interfaces. Regarding the HER, the synthesized MCM@CNT-N heterostructure catalyst showed high efficiency and stable electrocatalytic performance, with a low overpotential of 174.2 mV and a small Tafel slope of 84.7 mV dec−1 at a current density of 10 mA cm−2 in 0.5 M H 2 SO 4. In addition to the function of heterojunctions, the excellent activity is also attributed to the introduction of Co and N atoms and the formation of carbon nanotubes. This work provides a new approach to build efficient and low-cost electrocatalysts for electrochemical reactions. [ABSTRACT FROM AUTHOR]