Rational construction of N-containing carbon sheets atomically doped NiP-CoP nanohybrid electrocatalysts for enhanced green hydrogen and oxygen production

Abstract

The pursuit of sustainable energy production has directed rigorous research in the field of electrocatalysis, particularly for water electrolysis (i.e., hydrogen evolution (HER) and oxygen evolution reactions (OER)). This study discloses the rational synthesis of N-containing carbon sheets atomically doped NiP-CoP nanohybrid (NiP-CoP/NCS) via precipitation/calcination. The fabrication method tailored the physicochemical merits for collective contribution to improved green hydrogen and oxygen production, elucidated by surface/bulk characterization and theoretical calculations. Thus, the NiP-CoP/NCS had improved HER activity at lower overpotential (ƞ10 = 197.7/274.6 mV), higher exchange current density (jo = 0.71/0.67 mA/cm2), turnover frequency (TOF = 2.63/1.47 s-1), H2 production rate (3601.63/2519.12 µmol/g/h) and superior stability after 24 h in acid/alkaline media, than NiP/NCS and CoP/NCS. Moreover, NiP-CoP/NCS delivered impressive OER activity at reduced ƞ10 (309.1 mV), and Tafel slope (ba = 58.9 ± 3.0 mV/dec), but higher TOF (3.67 s-1) and O2 production rate (3643.96 µmol/g/h) relative to NiP/NCS and CoP/NCS, besides higher stability for 24 h. These were further proved by theoretical calculations. This work indicates a deeper understanding of the fabrication methods of making efficient electrocatalysts for green and sustainable energy conversion.