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Low-cost, stable, and high-efficiency electrocatalysts are highly demanded for large-scale hydrogen production by industrial-scale water electrolysis. The rational interface and defects engineering of the electrodes can effectively modify the active sites and promote electron transfer, thus facilitating the electrocatalytic splitting efficiency. In this work, spherical MoSe2/MoS2 heterojunction nanosheets are in situ anchored on nitrogen-doped carbon nanotubes/carbon cloth (N-CNTs/CC) struts. The porous and highly conductive N-CNTs/CC networks can improve the electron transfer, enlarge the exposed surface area, and facilitate the surface ion adsorption. Moreover, the influence of the Se/S ratio on the structure of the composites is also investigated. Afterward, abundant electron-rich defects and vacancies are introduced by the phosphorization process. The MoSe2/MoS2 heterojunctions with abundant interface can provide synergetic interactions and electronic modulations, while the PO4 3– dopant can expand the interlayer spacing and provide sufficient crystalline distortions and defects. Herein, the rational designed hierarchical P-MoSe0.5S1.5/N-CNTs/CC-2 composite exhibits a low overpotential (108.3 mV) at 10 mA cm–2, a small Tafel slope (58.6 mV dec–1), and excellent long-term catalytic and structural stability.

Rational structural design of the electrodes with high electron conductivity, sufficient material interfaces/defects and regulated charge transfer pathway can be applied in broad practical electrochemical application fields. Triple-layered PPy@NiCo LDH/FeCo2O4...

The application of tin disulfide (SnS2) in electrochemical water splitting remains a challenging issue on account of its unsatisfactory intrinsic electron conductivity and electrocatalytic activity. In this work, the vertically aligned SnS2 nanosheet arrays with open porous mass transfer pathways are synthesized, while the rational surface modification of highly electrocatalytic active heteroatoms (Ni/Fe or Ru) onto the SnS2 surface is achieved by a cation exchange strategy. The as-prepared Ni/Fe dual-metal-doped SnS2 on carbon cloth (NiFe-SnS2/CC) with abundant S vacancies and Ru nanodots-modified SnS2 (Ru-SnS2/CC) with SnS2/SnS heterostructures can effectively enhance the electron conductivity and the electrocatalytic activity. Benefiting from the plenty of metal heteroatoms and defects, the onset overpotential of the NiFe-SnS2/CC composite is only 251 mV for oxygen evolution reaction, while the value of Ru-SnS2/CC is 81 mV for hydrogen evolution reaction, along with robust long-term durability. Moreover, the assembled NiFe-SnS2/CC-3||Ru-SnS2/CC-10 electrolyzer device can attain a low cell voltage of 1.576 V at 10 mA cm–2. This project provides the methodology for promoting the low electrocatalytic species for high-performance energy conversion as well as a rational surface modification strategy through a cation exchange reaction.

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