Ni-P/TRANSITION METAL-DOPED C3N4 FOR HYDROGEN GENERATION FROM SEAWATER

Abstract

A pressing demand exists for economical and exceptionally efficient electrocatalysts capable for renewable and clean energy. Nickel phosphides (NiP) and carbon nitride (CN), separately, have garnered significant attention in the exploration of electrocatalytic hydrogen evolution reactions (HER), owing to their noteworthy activity and durability. Nevertheless, devising convenient and scalable methods for crafting NiP structures with exceptional HER performance for real-world applications remains a formidable challenge. In this study, CNs with distinct shapes of fibrous (i.e., CNF) and tubular (CNT) were embedded with NiP, to afford (CNF@NiP and CNT@NiP), respectively via electroless deposition. A promoter of ultra-small platinum (Pt) atoms were further doped in CN and incorporated into the CNF@NiP and CNT@NiP to yield (CNF/Pt@NiP and CNT/Pt@NiP) to augment the HER activity and stability investigated in simulated seawater (i.e., 3.5 wt.% NaCl solution).The physicochemical features of the electrocatalysts were determined by various characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDX) mapping, transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). While the HER measurements were rigorously evaluated by different electrochemical techniques: cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectroscopy (EIS. Among the studied electrocatalysts (CNF/Pt@NiP, CNT/Pt@NiP, CNF@NiP, CNT@NiP and NiP) for HER electrocatalysis in the simulated seawater, the CNF/Pt@NiP exhibit a better HER activity at low ƞ10 (0.50 V) and high jo (0.3496 mA/cm2), compared to; CNT/Pt@NiP (0.56 V; 0.3182 mA/cm2), CNF@NiP (0.55 V; 0.2095 mA/cm2), CNT@NiP (0.0063 mA/cm2) and NiP (0.0345 mA/cm2). Also, the EIS analysis showed an extremely high CNF/Pt@NiP-simulated seawater interfacial interaction that led to a high corrosion resistance, which is beneficial for its superior HER stability. The enhanced HER electrocatalysis of CNF/Pt@NiP was due to lower lattice spacing and contraction of Ni {111} facet, downshifted d-band center of NiP on incorporation of ultra-small Pt atoms, enhanced electron density and optimized synergism. This thorough investigation offers valuable perspectives for formulating novel materials in relevant applications.