Carbon Nanotubes Fully Covered With Coral-shaped NiFe Film For Overall Water Splitting

It is undeniably a critical development towards a hydrogen economy to develop active,stable,earth-abundant,and low-cost bi-functional electrocatalysts that can facilitate both the oxygen evolution reaction and hydrogen evolution reaction in the same electrolyte.Developing electrocatalyst by integrating nonprecious metals with nanocarbon has been an effective strategy to maximize an electrocatalyst’s catalytic performance.This 3D hybrid electrocatalyst exposes abundant active sites and enhanced intrinsic activity.Binder-free Carbon nanotubes supported on carbon fiber cloth with excellent conductivity and good mechanical stability improve the electrocatalyst’s electron transport capability.It is also beneficial to the exposure of active sites,bubbles escape,and contact with electrolyte during the electrolysis.In this research work,we have successfully developed an integral catalytic material（（CNT@Ni Fe）/（CFC@Ni））fabricated with carbon nanotubes onto carbon fiber cloth substrate,followed by electrodeposition of Nickel and Iron for the overall water splitting reaction.The3D structured carbon nanotubes were stably grown onto carbon fiber cloth via the chemical vapor deposition method offering a large surface area.The（CNT@Ni Fe）/（CFC@Ni）shows good stability and strong bubbles generation in an extensive current water-splitting process.The（CNT@Ni Fe）/（CFC@Ni）also shows excellent carbon corrosion resistivity during the oxygen evolution reaction due to the utilization of a large surface area ratio governed by fully covered carbon nanotubes with catalyst films.Consequently,this（CNT@Ni Fe）/（CFC@Ni）requires an overpotential of only 242 m V for oxygen evolution reaction and 195 m V for hydrogen evolution reaction to obtain a current density of 30 m A.cm^-2 in 1M KOH.Furthermore,it possesses good stability in long-term stability tests by maintaining the overpotential for 100hours at a constant current density of 50 m A.cm^-2 during the OER and HER reactions.When applied as both anodic and cathodic electrodes in overall water splitting reaction,this integral catalytic material achieved a current density of 100,300,and 500 m A.cm^-2 at a cell voltage of only 1.59.1.75 and 1.87 V,respectively.It also shows good long-term durability at a constant current density of 100 m A.cm^-2 for 32 hours.