Preparation And Photoassisted Electrocatalytic Performance Of Cobalt Nitride Porous Nanowires

With the rapid development of the new era,the demand for traditional fossil fuels is also increasing.Due to the excessive use of traditional fossil fuels,there are many unfavorable problems have arisen,such as the energy crisis and environmental pollution problems.Therefore,there is an urgent need to exploit clean renewable energy sources to replace the fossil energy.Hydrogen,a high-calorie,non-polluting clean energy source,brings a great hope to solve the energy shortage and environmental pollution problems.Electrochemical water splitting is an efficient energy conversion strategy.At present,Pt foil and Pt-based catalysts exhibit the most excellent catalytic activity for Hydrogen evolution reaction（HER）,IrO₂ and RuO₂ exhibit high-performance catalytic properties for the Oxygen evolution reaction（OER）.However,their high cost and the low reserves limit their extensive application.In the case,it is imperative to develop low-cost catalysts for HER and OER.Photocatalytic water splitting is also a method of preparing high-purity hydrogen gas.The advantage is that sunlight is used to drive the reaction,and the disadvantage is that the generated photocurrent is low.Considering the combination of the two methods for water splitting,it can improve the rate of hydrolysis,but also the consumption of electrical energy can also be reduced.Cobalt-based catalysts exhibit excellent catalytic performance in electrochemical water splitting.In this paper,we designed cobalt nitride porous nanowire arrays on carbon cloth（CC）as bifunctional electrocatalysts for overall water splitting.The morphologies and mechanisms of the samples were characterized by scanning electron microscope,transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectrometer.The results show that the cobalt nitride porous nanowires have a length of about 7μm and a diameter of about135 nm.The size of the particles is between 5-20 nm,and the cobalt nitride nanowires have a high crystallinity.In this paper,a standard three-electrode system was used to test the catalytic performance of the self-supported cobalt nitride porous nanowire for HER and OER.As a result,the self-supported,binder-free electrodes exhibit excellent catalytic activities with low overpotentials of 97 mV for HER and 251 mV for OER at the current density of 10 mA cm^-2in 1.0 M KOH.In addition,the electrocatalytic activities of the CoN-400/CC electrode have been improved after light irradiation owe to its strong absorption in the ultraviolet visible range.Considering that the self-supported cobalt nitride porous nanowire material is a noble metal-free and highly active bifunctional electrocatalyst,Therefore,The alkaline water electrolyzer with the self-supported porous nanowire arrays as cathode and anode requires a cell voltage of 1.587 V to achieve a current density of 10 mA cm^-2 and shows long-term stability at the high current density(³60 mA cm^-2)over 37 hours,favorably comparable to the integrated performance of commercial Pt and IrO₂.In view of the excellent performance of cobalt nitride electrode,it is a promising bifunctional electrocatalyst for practical application.