Synthesis Of Cobalt-Based Transitional Bimetallic Catalysts And Their Properties For Electrochemical Oxygen Evolution

Electric decomposition of water is a good way that it produced hydrogen energy.It's without pollution,high purity to sustainable and environmentally friendly preparation of hydrogen.The method is regarded as a change energy crisis and the important means of sustainable hydrogen energy development.Oxygen evolution reaction?OER?is the key path in the process of water splitting.There are four protons and electrons transferred in the OER,which belongs to sluggish kinetics.Cobalt?Co?3d orbital electron configuration is t⁶_2ge¹_2g,a low spin electron is close to the filling state of e⁰_2g.The electron transport for OER catalysis is often applied to OER electrocatalysis.When Co is combined with another transition metal element,the catalytic performance of Co can be further improved by means of electron,composition,and morphological regulation effect.Therefore,in this paper our mainly designed and synthesized kinds of transitional bimetallic catalyst:sheet-like CoZn-LDH,fernwort-like CoFeS₂@C and tremella-like CoNi-MOFs@C.The glassy carbon electrode?GCE?were modified by bimetallic catalyst,which were used electrochemical performance of oxygen evolution reaction.The main research is as follows:?1?In this work,at room temperature the sheet-like CoZn-LDH was synthesized by a co-precipitation method which using ZnSO₄·7H₂O?Co?AC?₂·4H₂O and MeIM as raw material.The morphology and structure of the materials were characterized by X-ray diffraction?XRD?,Fourier transforming infrared spectrum?FT-IR?,N₂ adsorption-desorption isotherms?BET?,Scanning electron microscope?SEM?and Transmission electron microscopy?TEM?.There was also pointed out that the MeIM as raw material has an alkaline effect and morphological regulator.The polarization curve of CoZn-LDH,which presents a low onset potential of¹.55 V?vs.RHE?.The sheet-like CoZn-LDH catalysts exhibits excellent activity and stability,with an overpotential of 385 mV at 10 mA cm^-2 and a Tafel slope of 108 mV dec^-1.But the OER catalytic current of CoZn-LDH at high potentials?>1.67 V vs.RHE?has been exceeded catalytic of commercial RuO2.Our sheet-like catalysts of CoZn-LDH better than RuO2.It was found that the OER current density of CoZn-LDH was dropped initially and then stabilized at 10 mA cm^-2 for a period of 8.0 h.The results demonstrate that the CoZn-LDH was a promising catalyst for OER with high activity and strong stability.?2?In this work,the fernwort-like CoFeS₂@C was synthesized by a hydrothermal method which using Co?NO₃?₂·6H₂O,Fe?NO₃?₃·9H₂O,glucose and thiocarbamide as raw material.The morphology and structure of the materials were characterized by XRD,SEM,BET,FT-IR and TEM.The polarization curve of fernwort-like CoFeS₂@C,which presents a low onset potential of¹.50 V?vs.RHE?.The fernwort-like CoFeS₂@C catalysts exhibits excellent activity and stability,with an overpotential of360 mV at 10 mA cm^-2 and a Tafel slope of 109 mV dec^-1.However,the RuO₂ afforded a current density of 10 mA cm^-22 at an overpotential of 375 mV and a Tafel slope of 115mV dec^-1.The fernwort-like CoFeS₂@C better than RuO₂.The OER current density of fernwort-like CoFeS₂@C was dropped initially and then stabilized at 10 mA cm^-2 for a period of 10.0 h.The results demonstrate that the fernwort-like CoFeS₂@C was a promising catalyst for OER with high activity and strong stability.?3?In this work,the tremella-like CoNi-MOFs@C was synthesized by a hydrothermal method which using Co?NO₃?₂·6H₂O,Ni?NO₃?₂·6H₂O,glucose and MeIM as raw material.The morphology and structure of the materials were characterized by XRD,SEM,BET,FT-IR and TEM.The polarization curve of tremella-like CoNi-MOFs@C,which presents a low onset potential of¹.50 V?vs.RHE?.The tremella-like CoNi-MOFs@C catalysts exhibits excellent activity and stability,with an overpotential of 330 mV at 10 mA cm^-2 and a Tafel slope of 108 mV dec^-1.However,the RuO₂ afforded a current density of 10 mA cm^-22 at an overpotential of 369 mV and a Tafel slope of 115 mV dec^-1.The tremella-like CoNi-MOFs@C better than RuO₂.The OER current density of tremella-like CoNi-MOFs@C was dropped initially and then stabilized at 10 mA cm^-2 for a period of 24.0 h.The results demonstrate that the tremella-like CoNi-MOFs@C was a promising catalyst for OER with high activity and strong stability.