Activation of urchin-like Ni-doped W18O49/NF by electrochemical tuning for efficient water splitting

The electrochemical conversion is closely correlated with the electrocatalytic activities of the electrocatalyst. Herein, the urchin-like Ni-doped W18O49/NF with enriched active sites was prepared by solvothermal method followed by a low-temperature pyrolysis treatment was reported. Results demonstrate that the incorporation of Ni-doping triggers the lattice distortion of W18O49 for the increasement of oxygen defects. Further, high-valent W6+ are partially reduced to low-valent W4+, wherein the electrons originate from the oxidation process of Ni2+ to Ni3+. The Ni3+ ions show an enhanced orbital overlap with the OER reaction intermediates. The generated W4+ ions contribute to release oxygen vacancies, eventually reorganizing Ni-doped W18O49/NF to unique electrochemical active species with a special amorphous-crystalline interface (AM/NiWOx/NiOOH/NF). Simultaneously, the reconstruction results in an optimized valence band and conduction band. Eventually, the resultant AM/NiWOx/NiOOH/NF with abundant active sites and improved oxidation/reduction capability exhibits more superior catalytic performance compared with the Ni-doped W18O49/NF counterpart. This study gives more insights in the electrochemical evolution of the tungsten-based oxide and provides effective strategies for optimizing the catalytic activity of materials with inherent hydrogen evolution reaction limitations.