Multifunctional electrocatalyst of NiCo-NiCoP nanoparticles embedded into P-doped carbon nanotubes for Energy-Saving hydrogen production and upgraded conversion of formaldehyde

Herein, we report the linearly distributed NiCo-NiCoP nanoparticles embedded into P-doped carbon nanotubes (NiCo-NiCoP@PCT) which are synthesized via the chelation of phytic acid (PA) on the surface of Ni-Co-precursor nanowires and the subsequent thermal reduction. The PA is used not only as chelating agent to form Ni-Co@PA coating but also as solid phosphorus source to safely synthesize heterostructured NiCo-NiCoP. The as-prepared NiCo-NiCoP@PCT used as bifunctional electrodes exhibit superiorly electrocatalytic performance toward both hydrogen evolution reaction (HER) with a low overpotential of 135 mV at 10 mA cm-2 and anodic oxidation reaction of formaldehyde (FOR) with an ultra-low overpotential of 1.18 V to acquire 10 mA cm-2. Besides, when a two-electrode cell is constructed by using NiCo-NiCoP@PCT as anode and cathode, the current density of formaldehyde-based water electrolysis (50 mA cm-2) is 6.25 times bigger than that of conventional water splitting (8 mA cm-2) at the same voltage of 1.76 V. In addition, methanol (CH3OH) is produced simultaneously by hydrogenation reduction reaction of formaldehyde at the cathode, which realized the upgraded conversion of HCHO to small molecular fuel by electrocatalytic reduction. Therefore, it is demonstrated that the two-electrode electrolyzer not only realize the oxidative degradation and upgraded conversion of formaldehyde-based wastewater, but also reduce the energy consumption of water splitting for hydrogen generation. This work presents a new idea of controllable preparation for multifunctional phosphide electrodes and a novel construction of electrochemical cell to realize efficient hydrogen energy preparation and environmental management.

Automated summary

In this work, linearly distributed NiCo-NiCoP nanoparticles embedded into P-doped carbon nanotubes (NiCo-NiCoP@PCT) were synthesized through the chelation of phytic acid (PA) on the surface of Ni-Co-precursor nanowires and subsequent thermal reduction. The as-prepared NiCo-NiCoP@PCT exhibited superior electrocatalytic performance for both hydrogen evolution reaction (HER) and formaldehyde oxidation reaction (FOR). When used as anode and cathode in a two-electrode cell, NiCo-NiCoP@PCT showed efficient hydrogen energy preparation and oxidative degradation of formaldehyde-based wastewater.