Preparation And Electrochemical Properties Of Transition Metal Cobalt/Nickel-Based Composites

With the rapid development of social economy,energy and environmental problems have become increasingly severe.In the past few decades,in order to solve these two major problems,researchers have explored and developed various new renewable energy sources,such as solar energy,wind energy and tidal energy.But these new energy sources have the disadvantage of low utilization.Thence,energy conversion and storage systems are the key to achieving efficient use of renewable energy,and their development and utilization are imminent.Lithium ion batteries（LIBs）and sodium ion batteries（SIBs）are energy storage devices with higher energy density and better rate performance.Hydrogen energy is also a new type of energy source that is clean,pollution-free,and has a high energy density.Electrochemical water splitting technology can efficiently convert electrical energy into hydrogen energy.This article mainly starts from two perspectives of efficient use of new energy and development of new energy（hydrogen energy）.Therefore,the lithium storage/sodium storage performance and electrocatalytic activity of the designed transition metal cobalt/nickel-based composite materials were studied.（1）The carbon layer is one of the suitable strategies to increase the conductivity of the nanoparticle material and limit its volume expansion.At the same time,doping nitrogen atoms（N）and phosphorus atoms（P）in the carbon layer can further enhance the electrochemical performance.In this chapter,Ni₂P@N,PC/rGO composites are prepared by simple hydrothermal and subsequent phosphating heat treatment methods.As an anode material for LIB and SIB,electrochemical studies have shown that Ni2P@N,PC/rGO-0.4 electrode still shows an excellent ratio of 450 m A h g-1 after2000 cycles at 5 A g-1 in LIB Capacity,with good cycle stability.（2）The rational design of high-performance electrocatalysts for overall water splitting is of vital importance for the future development of the energy field.In this chapter,a unique solid phase reaction（SPR）route is proposed to synthesize Ru/RuO₂/Co₉S₈/Co₃O₄（RRCC）nanohybrids for electrolysis of water by convenient hydrothermal and subsequent heat treatment processes.The resulting RRCC hybrid nanomaterial exhibits high performance for the hydrogen evolution reaction（HER）.（3）In this chapter,the Ru/RuO₂/NiCo₂S₄/Ni CoO₂/Co SO₄（RRNNC）nano-hybrid was prepared along the solid-phase reaction route for electrocatalytic water splitting.In the 1M KOH alkaline solution,the resulting RRNNC hybrid nanomaterials only required a 28 m V overpotential to reach a current density of 10 m A cm^-2 in the HER test,which was better than Pt/C（26 m V）.In the OER reaction,only an overpotential of 212 m V is required to achieve 10 m A cm^-2,which is superior to commercial RuO₂catalysts.In addition,the two-electrode analyzer with the RRNNC series catalyst as the cathode and anode can reach a current density of 10 m A cm^-2 at a battery voltage of1.50 V,which is also better than the Pt/C/NF//RuO₂/NF electrode.