| Hydrogen production from water spliting has already begun its industrial application for the convenint operation,pure hydrogen outputs and the abundant resources.However the anode process is dominated by a four-electron-proton transfer reaction to evolute oxygen.To proceed those steps,a high activation energy is needed to overcome the polarization,otherwise a low hydrogen production efficency will be demonstrated.Currently,the catalyst been reported mostly owns a high overpotential and poor stability that cannot meet the criteria of the industry.What's more,the catalyst produce in lab are overwhelming power catalyst,which certainly harms the catalytic efficiency for the reason that Nafion decreased the conductivity of the electrode.In this dissertion,a new promising PED method is employed to synthesis the high efficiency and stability film catalyst by which the transition metals and N doped graphene co-deposited on the surface of TC4.Further research such as SEM and XPS was introduced to charaterize the film catalyst and optimize the PED electrolyte.The OER film catalyst with different active site content was prepared by the plasma deposition(PED)method in aqueous phase and organic phase system.The films prepared at different time conditions were evaluated by oxygen evolution reaction.It is found that the catalyst prepared by the 70 min in the organic phase system is only 0.2V when the current density is 10 m A/cm2,and the Rct is only 0.04 Ohm when the area of the electrode is 5cm2,and the double layer capacitance is 0.3308 m F/cm2.The catalytic efficiency has not changed after 48000 s stability test.The above data are obviously better than those of other process catalysts.In order to further clarify the active sites of the catalyst prepared by PED method,the phase analysis of OER catalysts prepared at different time conditions was carried out.The results of XRD analysis show that the shifted peak of the Fe Ni alloy exists in the phase,and the Raman test further shows that the doped graphene existed,and the Fe is in the form of oxidation.It is therefore speculated that there are at least two active components in the film catalyst.The results of XPS analysis show that the binding of Fe2 p and N1 s shifted at the same time,indicating the existence of Fe-N-C bond.By semi quantitative analysis,the content of Fe-N-C in O-70 catalyst is about 5%.XPS high resolution map can obtain the content of Fe-N-C coupled active sites of OER catalyst.By comparing the overpotential of LSV 10 m A/cm2 and the conversion frequency(TOF)data of the coupling active site,it was found that the content of the active site of Fe-N-C could decrease the overpotential and the turnover frequency of the active site.It indicates that Fe-N-C is the main active component of the catalyst prepared by PED method.For purpose to clarify the active sites and illustrate the mechaism of synergistic catalytic effect,the catalyst prepared by PED were analysed by XPS.The result shows that two or three active site coupled active site were successfully synthesised,which are proportional to the turnover frequency under the overpotential 300 m V and overpotential under the 10 m A/cm2 current density inverse.In order to accurately calculate the number of coupled active sites,it's necessary to further clarify whether the carbonyl existed in the edge of the graphene oxidated in the air contributes to the catalytic activity.A chemical vaper deposition experiment was designed and executed on the surface of TC4 by C?O co-deposition and the result stastictically support the Fe-N-C coupled active site for the poor activity of carbonyl. |
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