Lotus root-like porous carbon nanofiber anchored with CoP nanoparticles as all-pH hydrogen evolution electrocatalysts

The development of highly active and cost-effective hydrogen evolution reaction （HER） catalysts is of vital importance to addressing global energy issues. Here, a three-dimensional interconnected porous carbon nanofiber （PCNF） membrane has been developed and utilized as a support for active cobalt phosphide （COP） nanoparticles. This rationally designed self-supported HER catalyst has a lotus root-like multichannel structure, which provides several intrinsic advantages over conventional CNFs. The longitudinal channels can store the electrolyte and ensure fast ion and mass transport within the catalysts. Additionally, mesopores on the outer and inner carbon walls enhance ion and mass migration of the electrolyte to HER active CoP nanoparticles, thus shortening the ion transport distance and increasing the contact area between the electrolyte and the CoP nanoparticles. Moreover, the conductive carbon substrate provides fast electron transfer pathways by forming an integrated conductive network, which further ensures fast HER kinetics. As a result, the CoP/PCNF composites exhibit low onset-potentials （-20, -91, and -84 mV in 0.5 M H2SO4, 1 M PBS, and 1 M KOH, respectively）. These findings show that CoP/PCNF composites are promising self-supporting and high-performance all-pH range HER catalysts.