Aligned NiP2/CoP2 nanoneedle arrays obtained over carbon fiber paper by selective temperature control for efficient HER electrocatalysis

Abstract

We propose coupling of hydrothermal-synthesis with the high-temperature phosphorisation step for the direct growth of optimized morphology (nanoneedle arrays) and composition (NiP2/CoP2) of NiCo-phosphide (NCP) on carbon fiber paper. Cathodic H2 evolution (HER) depicts the morphology and composition-dependent kinetics. The electrocatalysts prepared at phosphorisation temperatures of 300 °C (NCP-300), 400 °C(NCP-300), and 500 °C(NCP-300) depicted the overpotentials of 96 mV, 71 mV, and 80 mV respectively for the generation of cathodic current equivalent to10 mAcm−2. The overpotentials required for generation of 100mAcm−2 are 155 mV, 126 mV and 185 mV for NCP-300, NCP-400 and NCP-500 respectively.