Enhancing hydrazine-assisted hydrogen production by constructing CoP-Co2P bifunctional catalysts

The development of bifunctional catalyst is very important for hydrazine-assisted hydrogen production. Herein, the CoP-Co2P@CC-300 composites self-supported on carbon cloth (CC) were prepared by chemical reduction coupling phosphating method. The required voltages of HER (-61 mV) and HzOR (-89 mV) on CoP-Co2P@CC-300 are comparable to or exceed that reported at 10 mA cm-2, which is mainly attributed to the high dispersion and intrinsic activity of CoP-Co2P nanoparticles, and good conductivity of CoP-Co2P@CC-300. Furthermore, the overall hydrazine splitting (OHzS) electrolyzer was assembled by using CoP-Co2P@CC-300 electrodes, and the required cell voltage for the OHzS is only 37 mV at 10 mA cm-2, which is lower than or comparable to that reported. The OHzS electrolyzer can still achieve efficient hydrogen production under same conditions except that power source is a dry cell or a solar panel. The DFT calculation shows that the excellent performance of CoP-Co2P@CC-300 is mainly ascribed to that CoP-Co2P can reduce the adsorption free energy of hydrogen (Delta GH*) in HER process and the energy barrier of the rate-limiting step (dehydrogenation of * N2H2 to *N2H) in HzOR process. The work provides a novel idea for hydrazine-assisted hydrogen generation by using waste dry cells or solar panels as power source.

Automated summary

In this study, CoP-Co2P@CC-300 composites self-supported on carbon cloth were prepared and showed excellent catalytic activity in hydrazine-assisted hydrogen production. The required voltages for hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) on CoP-Co2P@CC-300 were comparable or even higher than that reported at 10 mA cm-2, indicating its high performance. Furthermore, an overall hydrazine splitting (OHzS) electrolyzer was assembled using CoP-Co2P@CC-300 electrodes, and it achieved efficient hydrogen production with a low cell voltage of 37 mV at 10 mA cm-2.