| With the extensive use of fossil energy,the problems of environmental pollution and energy shortage have become increasingly prominent.In order to alleviate and solve these problems and realize the goal of"carbon neutra lity"as soon as possible,clean renewable energy is the best choice for us.Hydrogen energy has become a research hotspot in recent years due to its large com bustion energy and the combustion product being water.Among all kinds of hydrogen production,electrocatalytic water splitting for hydrogen stands out due to a series of advantages(for example,the H2 with high purity,simple equipment,and directly used in fuel cells,etc.).However,there are still some problems to be solved urgently,such as high overpotential and poor durability.At present,the best catalysts for water splitting are still precious metal catalysts represented by platinum,ruthenium,a nd iridium-based compounds,but their scarce reserves and high prices on the earth limit their commercial applications.Therefore,it forces us to explore other high-performance and stable catalysts.In recent years,people have successively developed exce llent electrocatalysts for water splitting based on transition metals.Copper-based nanocatalysts are favored by people in energy storage and conversion due to their relatively abundant reserves,low price,easy preparation,and multivalent states.However,the activity and durability are still unsatisfactory,when applied to electrocatalytic water splitting.Therefore,my research focuses on the appropriate modification of copper-based compounds to improve their electrocatalytic performance.The specific r esearch content is as follows1.Ammonia-induced synergistic construction of Co3O4@CuO microsheets:An efficient electrocatalyst for oxygen evolution reaction.The Co 3O4 and CuO composite nanomaterials were constructed by the Cu-N-Co coordination relationship.There are lots of Co3O4 nanoparticles uniformly dispersing on the CuO microsheet.Co3O4@CuO microsheets with the optimal ratio of Co and Cu showed good OER activity and excellent electrocatalytic stability.Studies have shown that the synergistic effect between Co3O4 and CuO and the regulation of the electronic structure after recombination,the electron transfer kinetics increases,which leads to the improvement of performance.This strategy can provide a new reference for the preparation of other high-activity electrocatalytic materials.2.Urchin-like hierarchical Co(OH)2@CuO nanostructures for high-efficiency electrolytic oxygen evolution reaction and electrochemical energy storage.The Co(OH)2 nanosheets were successfully coated on the surface of urchin-like CuO to fabricate Co(OH)2@CuO composites.The performance of electrocatalytic oxygen evolution and capacitance can be improved by adjusting the content of Co.For alkaline OER,Co(OH)2@CuO-2 showed the lowest overpotential(361 m V)could drive a current density of 10 m A cm–2.After 30 hours test,the current density could still be maintained above 90%.In addition,when the composite material was applied to the test of supercapacitor,it also displayed a higher s pecific capacitance of 270.8 F g–1 at 0.5 A g–1.These excellent catalysis and energy storage per formances suggest that this strategy for preparing composite catalysts is effective,and it is also hopeful that it can be applied to the preparation of cataly sts in other energy fields.3.P-doped hollow Co(OH)2@Cu2S nanotube arrays for overall water splitting.nanoarrays are beneficial to electrocatalytic performance due to fast electron transport and large surface area.In this view,the hollow P-Co(OH)2@Cu2S nanotube(P-Co(OH)2@Cu2S NTs)array structure was succesffully fabricated through the surface oxidation,sulfurization,alkaline etching and NH4Cl-assisted electrodeposition strategy.The catalyst exhibits excellent OER,HER and overall water spiltting activity because of the P doping and the three-dimensional layered structure with the combination of two-dimensional nanosheets and one-dimensional nanotube arrays.In 1 mol dm–3 KOH electrolyte,OER and HER can drive a current density of 50 m A cm–2 when the overpotentials of OER and HER are 285 m V and 325m V,respectively.When used for overall water splitting,20 m A cm–2 can be obtained at 1.59 V.In addition,the current density decreased slightly and shown excellent durability,when overall water splitting tested continuously for 48 hours.This preparation conditions of the catalyst are relatively mi ld,and it is promising to be applied to other energy conversion and energy storage systems.4.Chlorine-assisted synthesis of CuCo2S4@(Cu,Co)2Cl(OH)3 heterostructures with an efficient nanointerface for electrocatalytic oxygen evolution.Herein,chlorine assisted ion-exchange and in-situ sulfurization process were combined to develop Cu Co2S4@(Cu,Co)2Cl(OH)3 heterostructures from Cu(OH)2 nanoarrays.The chlorine element of cobalt source stimulated the formation of Co substituted Cu 2Cl(OH)3precursor,and facilitated its partial transformation to C u Co2S4 on the precursor surface to achieve composite structure with efficient nanointerface.The mixed valences of Co element(Co3+in Cu Co2S4 and Co2+in(Cu,Co)2Cl(OH)3)for the composite sample and O-S interpenetrated nanointerface between two component s provided low electron transfer resistance to get enhanced alkaline oxygen evolution reaction(OER)activities,on comparison to individual(Cu,Co)2Cl(OH)3 or Cu Co2S4samples.In 1 mol dm-3 KOH electrolyte,the overpotential reached 253 and 290 m V respectively at 20 and 50 m A cm-2,which is better than commercial Ir/C(281m V@20 m A cm-2).These findings may open up opportunities for the design of inexpensive and effective heterogeneous electrocatalysts through nanoi nterface engineering.5.Fe(OH)3@Sn-Cu2Cl(OH)3 core-shell nano-array structure for high-efficiency photoelectrocatalyic hydrogen evolution reaction.Photoelect rocatalytic water splitting is also an efficient hydrogen production strategy,and Cu-based nanomaterials are one of the excellent photoelectrocatalytic catalysts.Sn-substituted Cu2Cl(OH)3 nanowire arrays were obtained by ion exchange method,then the Sn-Cu2Cl(OH)3was etched by Fe3+ion and hydrolysis,causing Fe(OH)3@Sn-Cu2Cl(OH)3 core-shell nanowire array structure was finally obtained.It was directly applied to the photocathode.Compared with the original Cu(OH)2NAs/CF(120?A cm–2)and Fe(OH)3-Cu(OH)2 NAs/CF(233?A cm–2)electrodes,The photocurrent density of Fe(OH)3@Sn-Cu2Cl(OH)3 was increased by 6.5 times and 3.4times,respectively,reaching 785?A cm–2.Importantly,the photocorrosion was effectively suppressed.In addition,this modification s trategy can choose other elements such as Ag and Zn,which indicating that the strategy is universal.Last but not least,Fe(OH)3@Sn-Cu2Cl(OH)3 can also show better electrocatalytic oxygen evolution performance under alkaline conditions,indicating that the preparation strategy of this material has the potential to design multifunctional catalysts. |
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