Facile Aqueous\nRoute to Large-Scale Superhydrophilic\nTiO<sub>2</sub>‑Incorporated Graphitic Carbon Nitride-Coated\nNi(OH)<sub>2</sub> and Ni<sub>2</sub>P Nano-Architecture Arrays as\nEfficient Electrocatalysts fo

Water splitting by an electrochemical method to generate\nhydrogen\ngas is an economic and green approach to resolve the looming energy\nand environmental crisis. Designing a composite electrocatalyst having\nintegrated multichannel charge separation, robust stability, and low-cost\nfacile scalability could be considered to address the issue of electrochemical\nhydrogen evolution. Herein, we report a superhydrophilic, noble-metal-free bimetallic\nnanostructure TiO<sub>2</sub>/Ni<sub>2</sub>P coated on graphitic\npolyacrylonitrile carbon fibers (g-C/TiO<sub>2</sub>/Ni<sub>2</sub>P) using a facile hydrothermal method followed by phosphorylation.\nIn an aqueous-based route, PAN is dissolved in water in the presence\nof ZnCl<sub>2</sub>, followed by wet-spinning to prepare scalable\nPAN/ZnCl<sub>2</sub> fibers. The nitrogen-contained porous graphitic\ncarbon fibers are prepared via the pyrolysis of PAN/ZnCl<sub>2</sub> fibers; now ZnCl<sub>2</sub> acts as a volatile porogen to form\nporous matrix structures. Finally, the as-prepared graphitic carbon\nfibers are electrochemically activated by incorporating TiO<sub>2</sub>/Ni<sub>2</sub>P active sites. The materials formed in this work\nshow excellent electrocatalytic activity for the hydrogen evolution\nreaction. The as-synthesized g-C/TiO<sub>2</sub>/Ni<sub>2</sub>P catalyst\nshows a low overpotential, its electrocatalytic activity is improved,\nand its efficiency is better than that of the commercial Pt/C catalyst.\nAt a current density of −10 mA/cm<sup>2</sup>, the g-C/TiO<sub>2</sub>/Ni<sub>2</sub>P catalyst shows an overpotential of 55 mV,\nwhile the commercial Pt/C catalyst shows an overpotential of 77 mV.\nOur work provides a facile aqueous scalable route with no need for\nnoble metals that can be considered as a potential alternative for\nthe commercial Pt/C catalyst.