The Preparation And Electrocatalytic Overall Water Splitting Performance Study Of Nickel-based Phosphide Nanomaterials

In recent years,the clean and renewable features have driven hydrogen?H₂?to address the energy crisis and environmental problem.Electrocatalytic water splitting has been an extraordinarily appealing route to produce H₂ for the energy requirements and ameliorate the environmental issues.However,due to the existence of inherent energy barriers in the water splitting reaction,higher overpotential is required to get significant catalytic efficiency.Up till now,expensive Pt,Ir and Ru-based electrocatalysts have been the well-known most active catalytic materials for overall water splitting to reduce its overpotential.However,their large-scale application is seriously limited by exorbitant price and scarcity on earth.Nickle-based electrocatalysts have natural abundance,low cost,environmental-friendly and excellent catalytic activity advantages.The self-supported nickle-based electrocatalysts with excellent electrocatalytic activity were synthesized in this paper.The specific research contents of the thesis are as follows:?1?The 3D nanosheets arrays architecture,coupled with the modulation of surface structure and the incorporation of foreign atoms,construct an anticipated method to boost the electrocatalytic performance on the transition metal compounds-based non-precious catalysts.Herein,we report Fe-doped Ni₂ P nanosheets arrays supported on Ni foam by a simple hydrothermal method and phosphorization process,for enhancing electrocatalytic performance of both oxygen evolution?OER?and hydrogen evolution?HER?reactions.Benefitting from the increased electrochemical active sites and appropriate rough surface caused by surface engineering and the strong electronic effect derived from Fe-doping.The Fe-Ni₂P-2 nanosheets arrays can achieve the highest OER activity with a low overpotential of 255 m V at a current density of 100 m A·cm^-2 and a Tafel slope of 65.5 m V·dec^-1,better than the other catalysts with different phosphating rate.Moreover,the enhanced HER performance can also be obtained based on this distinct structure with a low overpotential of 204 m V at a current density of 100 m A·cm^-2 and a Tafel slope of 78.3 m V·dec^-1.Finally,a two-electrode alkaline electrolyzer,applying this optimized bifunctional catalyst as both the cathode and anode,can be driven with a low cell voltage of 1.54 V to afford a current density of 10 m A·cm^-2,as well as excellent stability.?2?The amorphous-phased material has high structural disorder,which is considered to be in favor of the electrocatalytic property.We report a Ni-Fe-P nanomaterial,which were in situ grown on 3D porous Ni foam by one-step electrodeposition method.When Ni:Fe=4:1 and electrodeposition for 10 min,as-prepared Ni-Fe-P material shows excellent bifunctional electrocatalytic performances in the 1.0 M KOH electrolyte.A small overpotential of 288 m V is achieved to reach a current density of 100 m A·cm^-2 for OER and an overpotential of 132 m V to afford a current density of 10 m A·cm^-2 towards HER.The Tafel slopes of Ni-Fe-P HER and OER are 63.03 m V·dec^-1 and 61.40 m V·dec^-1,respectively.Finally,a two-electrode alkaline electrolyzer,applying this optimized bifunctional catalyst as both the cathode and anode,can be driven with a low cell voltage of 1.54 V to afford a current density of 10 m A·cm^-2,as well as excellent stability.Such remarkable electrocatalytic performance can be attributed to the synergism of Ni and Fe elements,the amorphous holey structure and self-supportive configuration of the as-prepared Ni-Fe bimetal phosphide.The overall water splitting performance of above-mentioned two catalysts are at the forefront of most of as-reported catalysts,which provides new opportunities for achieving high-efficiency and low-cost bifunctional overall water splitting electrocatalysts.