Phosphine-free avenue to Co2P nanoparticle encapsulated N,P co-doped CNTs: a novel non-enzymatic glucose sensor and an efficient electrocatalyst for oxygen evolution reaction

Abstract

A novel one-step, one-pot strategy to synthesize Co₂P encapsulated N,P dual doped carbon nanotubes (Co₂P/NPCNTs) is developed via a g-C₃N₄ intermediated approach. The method uses readily available, inexpensive precursors without involving toxic phosphine gas (PH₃) during the phosphidation process. Moreover, the CNTs are synthesized and doped in situ without the aid of any external carbon additives. The morphology and structure were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The as-prepared Co₂P/NPCNTs were then for the first time demonstrated to be an electrochemical sensor for the enzymeless detection of glucose. The Co₂P/NPCNT-modified electrode exhibits a quick response and good linearity (R² = 0.997) up to 7 mM with a high sensitivity and a low detection limit (LOD) of 338.8 μA mM⁻¹ cm⁻² and 0.88 μM, respectively, towards glucose, selectively in the presence of various endogenous interfering agents such as D-sucrose, D-mannose, L-cysteine, urea etc. with a good long-term stability. When applied as an electrocatalyst for the oxygen evolution reaction (OER), Co₂P/NPCNT delivers a current density of 10 mA cm⁻² at an overpotential of 370 mV with a Tafel slope of only 53 mV dec⁻¹, outperforming even the state-of-the-art RuO₂ while maintaining excellent long-term durability.