Doped Transition Metal Compound Nanomaterials And Their Electrocatalytic Properties

Increasing environmental pollution and energy demands have prompted intense research to pursue and utilize sustainable alternative energy conversion technologies with low cost,high efficiency and friendly environments.Water splitting reaction has been considered as one of the most efficient ways for large-scale hydrogen production.The electrocatalytic water splitting can be divided into two halfreactions:the oxygen evolution reaction?OER?and the hydrogen evolution reaction?HER?,both of which are critical for high efficient overall water splitting.To date,platinum and RuO2 group noble metals are the most efficient catalysts for HER and OER,Unfortunately,their scarcity and high cost hinder their wide range of commercial application.Thus,it is of significance to find efficient and low cost non-precious metals catalysts.The heteroatom-doped transition metal catalysts have an adjustable electronic structure and good electrical conductivity,and can effectively improve the electrocatalytic activity of the transition metal compound material.In view of the limited application range of the transition metal electrocatalyst,the low catalytic activity and the unclear reaction mechanism,this paper has carried out a series of research works on the development and application of transition metal electrocatalysts,aiming to clarify the structure-activity relationship between catalyst structure and electrocatalytic performance,and to explore its internal reaction mechanism.It mainly includes the following contents:?1?Combining hydrothermal and low temperature phosphidation methods,V-doped Ni2P nanosheet arrays grown on carbon cloth?V-Ni2P NSAs/CC?were successfully prepared.The V-Ni2P NSAs/CC electrocatalyst exhibits excellent HER electrocatalytic activity and stability under alkaline conditions.The TEM5 EPR,XPS,and UPS characterizations studies system proved that its high activity derived from V doping has generated lattice defects,adjusting the electronic environment of the metal center of the catalysts,resulting in strong electronic interaction and synergistic effects between the elements.?2?The Cu-doped CoP nanorod array on carbon cloth?Cu-CoP NRAs/CC?was successfully prepared via a facile hydrothermal and thermal treatment methods,which demonstrate enhanced catalytic performance over a wide pH range.To obtain a current density of 10 mA cm-2,it need a low overpotentials of 44,81,and 137 mV in acid,basic,and neutral environments,respectively.It also maintains a stable catalytic activity under different pH condition.?3?The MnMoO4 nanosheet array was successfully prepared on the nickel foam by hydrothermal synthesis strategy,and realizing the electrocatalytic hydrogen evolution performance with high activity and high stability in the wide pH range,it demonstrates outstanding electrocatalytic performance and durability to drive current density of 10 mA cm₂ at low overpotentials of 89,105 and 161 mV in 0.5 M H2SO4,1 M KOH and 1 M PBS,respectively.Such preeminent HER performance may be derived from the synergistic effect and strong electronic interaction between manganese?Mn?and molybdenum?Mo?atoms.?4?The synthesis of a non-precious metal Cr-doped CoFe layered double hydroxide?Cr-CoFe LDHs/NF?electrocatalyst was realized by a one-step hydrothermal method.The catalyst has an ultra-low overpotential of 238 mV to obtain current density of 10 mA cm-2 in an alkaline solution?1 M KOH?and a high stability after 3000 cycles of testing.Density functional theory?DFT?calculations unveil that Cr dopants as new active sites could improve the electron-donation ability of the resultant Cr-CoFe LDHs due to the smaller electronegativity of Cr in comparison with Fe and Co.Therefore,the scaling relation of adsorption energy among four oxygen intermediates was broken and consequently the OER performance was further promoted.