Effect Of Carrier On Electrochemical Hydrogen Evolution Activity Of Ultra-low Loading Platinum Electrode

Excessive use of fossil energy is in many serious problems,such as environmental pollution caused by harmful gas emissions,gradual depletion of primary energy and non-renewable.Efficient,clean,environmentally friendly and renewable hydrogen energy has become a hot topic in the world.However,hydrogen production by electrolysis of water is an efficient and rapid way of environmental protection,simple and renewable access.In this paper,ultra-low load platinum electrode composites were successfully prepared by magnetron sputtering,hydrothermal method and displacement method(Pt_sub@Ru_HT@Co_MS),mainly studied the preparation method,morphology,electronic structure and electrochemical hydrogen evolution performance of its electrode material,and analyzed the reasons for its excellent hydrogen evolution activity.The main research contents are as follows:（1）By comparing low loads Pt_sub@Ru_HT/NF electrode physical characterization test analysis.The results of XRF characterization analysis indicate that Pt_sub@Ru_HT/NF the Pt load in the sample is only 0.823μg cm^-2,Ru load capacity 8.141μg cm^-2。Scanning electron microscopy（SEM）and transmission electron microscopy（TEM）were used to analyze the Pt_sub@Ru_HT/NFof morphology,element distribution,and lattice stripes.The distribution of Pt and Ru elements is uniform,with Ru（002）crystal plane spacing of 2.14（?）and Ru（100）crystal plane spacing of 2.34（?）.XPS analysis showed that the carrier Ru negatively shifted the binding energy peak of Pt,resulting in significant changes in its electronic structure,thereby improving the HER activity.In 0.5 M H₂SO₄,Pt_sub@Ru_HT/NF of the overpressure is 29 m V at a hydrogen evolution current density of 10 m A cm^-2;The apparent hydrogen evolution activity at200 m V is 235.6 m A cm^-2,2.32 times that of Pt_sub/NF.Pt_sub@Ru_HT/NF has a mass specific activity of 28.28 A mg^-1 at 200 m V,which is twice as active as commercial Pt/C-NF(14.13 A mg^-1).Pt_sub@Ru_HT/NF of the Tafel slopeis 40 m V dec^-1,indicating that Pt_sub@Ru_HT/NF of the hydrogen evolution reaction process on the surface electrode conforms to the Volmer-Heyrovsky mechanism.Pt_sub@Ru_HT/NF the charge transfer resistance（Rct）is 4.15Ω.cm²,which facilitates faster charge transfer during the HER process and is beneficial to improving hydrogen evolution activity.Prepared by three different preparation methods Pt_sub@Ru comparison of electrode HER activity,wherein Pt_sub@Ru_HT/NF has the best HER activity.When the hydrogen evolution current density is 10 m A cm^-2,Pt_sub@Ru_sub/NF、Pt_sub@Ru_MS/NF、Pt_sub@Ru_HT/NF of the overpotential is 214,33,and 29 m V,respectively;The apparent hydrogen evolution activity at 200 m V was 7.57,195.5,and 235.6 m A cm^-2,respectively.（2）Ultra-low platinum supported catalysts with special morphology and structure were prepared by introducing support metals M（Co,Ni,W,Fe）.Through XRF characterization analysis,Pt_sub@Ru_HT@M_MS/NF in the surface Pt loading amounts electrodes are 1.017,1.739,1.134,and 1.369,respectivelyμg cm^-2。Further analysis by SEM characterization method showed that Pt_sub@Ru_HT@Co_MS/NF of the surface of is a three-dimensional network structure connected by Co nanoparticles.Pt_sub@Ru_HT@Ni_MS/NF of the surface exhibits a planar network structure formed by the connection of dense Ni nanoparticles.Pt_sub@Ru_HT@W_MS/NF of the surface exhibits a dense array of spherical W nanoparticles,as well as a small amount of nano particle aggregates.The average size of W nanoparticles is about 40 nm.Pt_sub@Ru_HT@Fe_MS/NF spherical nanoparticles with different sizes are clustered on the surface.Moreover,the special morphology and structure of the catalyst have brought about a large electrochemical area（11.93,35,54,and 48 cm2,respectively）.Through XPS characterization analysis,due to the negative shift of the binding energy peaks of Pt and Ru caused by the non noble metal M_MS（Co,Ni,W,Fe）matrix,its electronic structure has significantly changed,thus improving the HER activity.And Pt_sub@Ru_HTcompared to the catalyst,the hydrogen evolution activity of HER has been greatly improved.Through electrochemical testing,in an acidic system Pt_sub@Ru_HT@Co_MS/NF-2 has excellent electrochemical hydrogen evolution activity,with an overpotential of 21 m V at a current density of 10 m A cm^-2 and a current density of575.5m A cm^-2 at an overpotential of 200 m V.Its hydrogen evolution activity is superior to that of the other three metals and Pt/C-NF(25μg cm^-2)。In addition,Pt_sub@Ru_HT@Co_MS/NF-2 the mass specific activity of the noble metal at 200 m V is56.34A mg^-1,and the Tafel slope is 48.25 m V dec^-1.In an alkaline system,Pt_sub@Ru_HT@Co_MS/NF-2 has an overpotential of 32 m V at a current density of 10 m A cm^-2;The current density reaches 116.3 m A cm^-2 at an overpotential of 200 m V,respectively.The Tafel slopes are 68.35 m V dec^-1,respectively.The above data indicate that the carrier Co pair Ru@Pt Its maximum catalytic effect and special morphology bring excellent hydrogen evolution activity to the catalyst.（3）Reply Pt_sub@Ru_HT@Coof the preparation of Co,Ru,and Pt on the bottom layer,middle layer,and surface layer was optimized.The effects of different preparation conditions on Pt_sub@Ru_HT@Co_MSof effect of the HER activity.Firstly,for the underlying Co,the effects of particle size,crystal surface,and oxidation degree were studied.The optimized electrode was characterized and analyzed by XRD Pt_sub@Ru_HT@Co_MS/Ti-100 in the particle size of Co is about 7.93 nm.When the hydrogen evolution current density is 10 m A cm^-2,the overpotential is 21 m V;The current density at 200 m V is 557.5 m A cm^-2.By treating the Co substrate at different temperatures（300℃～650℃）,the hexagonal Co（101）crystal surface at 47.34°at low temperatures will convert to the lower cubic Co（002）crystal surface at high temperatures,thereby affecting HER activity.Partial oxidation of the Co surface will increase HER activity Pt_sub@Ru_HT@Co_MS/NF-2%the overpotential of the electrode is15 m V at a hydrogen evolution current density of 10 m A cm^-2;The apparent hydrogen evolution activity is 438.55 m A cm^-2 Pt_sub@Ru_HT@Co_MS/NF-100 has a 6 m V reduction in overpotential compared to.Secondly,the loading amount of Pt and Ru is further optimized by changing the concentrations of Ru in the intermediate layer and Pt in the surface layer.When the concentration of Ru is 0.04 m M and the concentration of Pt is 0.008 m M,its mass specific activity is the highest.（4）Optimal activity for HER Pt_sub@Ru_HT@Co_MS electrodes for in-depth analysis.Firstly,XRF characterization analysis showed that the ultra-low load electrode Pt_sub@Ru_HT@Co_MS/NF in Pt load is 1.017μg cm^-2,Ru load capacity 8.879μg cm^-2。XPS characterization analysis showed that the carrier Co caused a negative shift in the binding energy peaks of Pt and Ru,resulting in significant changes in their electronic structures.Through TEM testing and characterization,it can be observed that Ru（002）crystal faces（2.14（?））,Ru（100）crystal faces（2.34（?））,and Co（101）crystal faces（1.93（?））.Electrochemical characterization analysis,Pt_sub@Ru_HT@Co_MS/NF（0.008 m M-100s）theelectrode has an overpotential of 21 m V and a current density of 557.5m A cm^-2 at an overpotential of 200 m V;The mass specific activity of the precious metal is 56.34A mg^-1 and the electrochemical area specific activity is 8.99 m A cm^-2.and Pt_sub@Ru_HT@Co_MS/NF of the charge transfer resistance（Rct）is 6.46Ω.cm²,which has a smaller charge transfer resistance,indicating that charge transfer is faster during the HER process.Test by chronoamperometry(η₁₀=20 m V)hydrogen evolution stability for up to 10 hours,Pt_sub@Ru_HT@Co_MS/NF of the decrease in hydrogen evolution current density was 9.8%.