Deciphering the In Situ Reconstruction of Metal Phosphide/Nitride Dual Heterostructures for Robust Alkaline Hydrogen Evolution Above 3 A cm-2.

Hydrogen evolution reaction (HER) in neutral or alkaline electrolytes is appealing for sustainable hydrogen production driven by water splitting, but generally suffers from unsatisfied catalytic activities at high current densities owing to extra kinetic energy barriers required to generate protons through water dissociation. In response, here, a competitive Ni3 N/Co3 N/CoP electrocatalyst with multifunctional interfacial sites and multilevel interfaces, in which Ni3 N/CoP performs as active sites to boost initial water dissociation and Co3 N/CoP accelerates subsequent hydrogen adsorption process as confirmed by density functional theory calculations and in situ X-ray photoelectron spectroscopy analysis, is reported. This hybrid catalyst possesses extraordinary HER activity in base, featured by extremely low overpotentials of 115 and 142 mV to afford 500 and 1000 mA cm-2 , respectively, outperforming most ever-reported metal phosphides-based catalysts. This catalyst presents an ultrahigh current density of 3545 mA cm-2 by a factor of 4.96 relative to noble Pt/C catalysts (715 mA cm-2 ) at 0.2 V. Assembled with Fe(PO3 )2 /Ni2 P anode, industrial-level current densities of 500/1000 mA cm-2 at ultralow cell voltages of 1.62/1.66 V for overall water electrolysis with outstanding long-term stability are actualized. More interestingly, this hybrid catalyst also performs well in acidic, neutral freshwater, and seawater requiring relatively low overpotentials of 140, 290, and 331 mV to reach 500 mA cm-2 . Particularly, this catalyst can withstand electrochemical corrosion without obvious activity decay at the industrial-level current densities for over 100 h in base. This work provides a cornerstone for the construction of advanced catalysts operated in different pH environments.

A novel and low-cost CuPc@C catalyst derived from the compounds of sunflower straw and copper phthalocyanine pigment for oxygen reduction reaction.

A series of carbon and phthalocyanine catalysts were prepared with uniform and stretchable sunflower straw biological materials as the carbon source and inexpensive copper phthalocyanine (CuPc) pigment as a nitrogen doping source by a facile high-temperature carbonization method. This kind of biomass carbon material sunflower straw with abundant pore structure and sponge-like expansion and contraction functions can not only be used as a source of porous carbon in biomass carbon materials, but also as a carbon carrier with high specific surface area to provide nanoparticle adhesion sites. When it was immersed in the copper phthalocyanine pigment solution, more active sites could be exposed, so that CuPc particles could be uniformly doped and distributed on the porous carbon material. As a result, thanks to the doping of nitrogen atoms and the improvement of graphitization degree, the composite catalyst treated at 800 °C (CuPc@C-800) exhibits a porous structure with a 38 mV lower on-set potential and a high stability of 87.4% compared to commercial Pt/C (20%) catalyst. These results demonstrate that CuPc@C series composite catalysts have a splendid electrochemical performance in oxygen reduction reaction catalysts, which can start a new direction for later workers to study combining the properties of biomass carbon material and the phthalocyanine series of catalysts.