磷化鈷納米棒作為一種高效電化學(xué)催化劑在析氫反應(yīng)過(guò)程中的應(yīng)用

1、Cobalt phosphide nanorods as an efficient electrocatalyst for the hydrogen evolution reaction磷化鈷納米棒作為一種高效電化學(xué)催化劑在析氫反應(yīng)過(guò)程中的應(yīng)用Zhipeng Huanga,n, Zhongzhong Chena, Zhibo Chena, Cuncai Lva, Mark G. Humphreyb, Chi Zhanga,n摘要（Abstract）Cobalt phosphide (Co2P) nanorods are found to exhibit efficient catalytic

2、activity for the hydrogen evolution reaction (HER), with the overpotential required for the current density of 20 mA/cm2 as small as 167 mV in acidic solution and 171 mV in basic solution. In addition, the Co2P nanorods can work stably in both acidic and basic solution during hydrogen production.Thi

3、s performance can be favorably compared to typical high efficient non-precious catalysts, and suggests the promising application potential of Co2P nanorods in the field of hydrogen production. The HER process follows aVolmerHeyrovsky mechanism, and the rates of the discharge step and desorption step

4、 appear to be comparable during the HER process. The similarity of charged natures of Co and P in the Co2P nanorods to those of the hydride-acceptor and proton-acceptor in highly efficient Ni2P catalysts, NiFe hydrogenase, and its analogues implies that the HER catalytic activity of the Co2P nanorod

5、s might be correlated with the charged natures of Co and P. & 2014 Elsevier Ltd. All rights reserved.磷化鈷納米棒（Co2P）被發(fā)現(xiàn)具有高效的催化性能在析氫反應(yīng)過(guò)程（HER），該過(guò)程所需的過(guò)電位在20 mA/cm2電流密度的情況下，在酸性溶液中盡可能小于167mV以及在堿性溶液中盡可能小于171 mV。此外，電子納米棒可以穩(wěn)定工作在酸性和堿性溶液中在整個(gè)析氫過(guò)程。這種性能可媲美的典型的高效的非貴金屬催化劑，并表明了Co2P納米棒在產(chǎn)氫領(lǐng)域中的廣闊應(yīng)用前景。析氫反應(yīng)過(guò)程遵循VolmerHe

6、yrovsky機(jī)制，并且放電步驟和解吸步驟的速率出現(xiàn)在析氫過(guò)程中具有可比性。Co2P納米棒的Co和P的帶電性質(zhì)與高效Ni2P催化劑,鎳鐵氫化酶以及它的相似物的氫受體和質(zhì)子受體類似，包括Co2P納米棒的析氫催化過(guò)程都與Co和P的帶電性質(zhì)相關(guān)聯(lián)。2014 Elsevier公司，保留所有權(quán)利相關(guān)。介紹（Introduction）The solar-driven splitting of water into molecular hydrogen and oxygen is one of the most promising possibilities forsimultaneously solvin

7、g the global energy crisis and current environmental issues 13. Because of the intrinsically slow hydrogen evolution reaction (HER) kinetics of semiconductors, photocathodes must be decorated with HER catalysts for efficient hydrogen production. Though platinum remains the most effective HER catalys

8、t, having been shown to significantly enhance the hydrogen production capability of photocathodes several decades ago 4,5, it is a limited resource and expensive, and so its widespread practicalapplication in the field of solar-driven hydrogen production may be limited. There is therefore a demonstr

9、able need for non-precious HER catalysts.太陽(yáng)能驅(qū)動(dòng)的水分子分解成分子氫和氧是同時(shí)解決全球能源危機(jī)和當(dāng)前環(huán)境問(wèn)題的最有前途的可能性 1 - 3 。由于半導(dǎo)體固有的析氫反應(yīng)（HER）動(dòng)力學(xué)緩慢，所以光電陰極必須用HER催化劑進(jìn)行高效制氫。雖然鉑仍是最有效的HER的催化劑，光陰電極在幾十年前已經(jīng)顯示出顯著的高效的產(chǎn)氫性能4,5，但是它是一種有限的資源，價(jià)格昂貴，所以在太陽(yáng)能制氫領(lǐng)域的廣泛應(yīng)用可能是有限的。因此，明顯需要一種非昂貴的HER催化劑。Recently, a variety of new HER catalysts have been reporte

10、d, including molybdenum sulfide 6,7, molybdenum carbide 810, molybdenum nitride 10, molybdenum boride 8, tungsten carbide 11,12, tungsten carbonitride 13, first-row transition-metal dichalcogenides 14,15, nickel selenide 16, nickel phosphide 17, cobalt phosphide (CoP) 1820, molybdenum phosphide 21,2

11、2, etc. The first-row transition-metal dichalcogenides have similar coordination structure as the active centers in efficient hydrogenase 15, and the charged natures of metal and P in metal phosphides are similar to those of the hydride acceptor and proton-acceptor in NiFe hydrogenase and its analog

12、ues (Ni(PS3n)(CO)1and Ni(PNP)22+) 23.近年來(lái)，各種新的HER催化劑已被報(bào)道，包括硫化鉬 6,7 ，碳化鉬8- 10 ，氮化鉬 10 ，硼化鉬 8 ，碳化鎢11,12，碳氮化鎢 13 ，第一行過(guò)渡金屬硫化物14,15，硒化鎳 16 ，磷化鎳 17 ，鈷磷化物（COP） 18-20 ，磷化鉬21,22等等。第一行過(guò)渡金屬硫化物在有效的氫化酶活性中心都具有相似的配位結(jié)構(gòu) 15 ，并且金屬磷化物的金屬元素和磷元素的帶電性質(zhì)和NiFe氫化酶及其類似物（Ni（PS3N）（CO）和鎳（PNP）2 2 +）的氫受體和質(zhì)子受體相似。 23 。Here the HER perf

13、ormance of cobalt phosphide (Co2P) nanorods is described. Although their structure and composition are different from all heretofore reported HER catalysts, the Co2P nanorods exhibit efficient and stable HER catalytic activity in both acidic and basic solutions. The overpotential required for a curr

14、ent density of 20 mA/cm2 (20) is as small as 167 mV in acidic solution and 171 mV in basic solution. The 20 of the Co2P nanorods lies in the top 10 of the reported values of non-precious HER catalysts. It is worth noting that the four reported 20 values better than that of the Co2P nanorods were obt

15、ained from composites of catalysts and nanostructured conductive supports, including Mo1Soy particles loaded on reduced graphene oxide (Mo1Soy/rGO) 10, CoP nanoparticles loading on carbon nanotube (CoP/CNT) 18, CoP nanowires loaded on carbon cloth (CoP/CC) 20, and MoS2 loaded on mesoporous graphene

16、foam (MoS2/MGF) 24. The nanostructured conductive supports are well known to improve electron transport among catalysts and therefore the performance of catalysts 25. The charged natures of Co and P in the Co2P nanorods are similar to those of the hydride-acceptor and proton-acceptor in Ni2P catalys

17、t, NiFe hydrogenase, and its analogues, which may explain the efficient catalytic activity of the Co2P nanorods.這里磷化鈷納米棒（Co2P）的HER催化表現(xiàn)被發(fā)現(xiàn)。雖然它們的結(jié)構(gòu)和組成不同于所有以前報(bào)道HER催化劑、磷化鈷納米棒在酸性和堿性溶液中都展現(xiàn)出高效、穩(wěn)定的HER催化活性。為20 mA/cm2的電流密度所需的過(guò)電位（20）是在酸性溶液中167和171 mV在堿性溶液中為小。電子的納米棒20在10大報(bào)告值的非貴她催化劑。值得注意的是，四日?qǐng)?bào)道20值優(yōu)于電子納米棒復(fù)合材料的催化劑

18、得到納米導(dǎo)電支持，包括mo1soy顆粒負(fù)載在石墨烯（mo1soy / RGO） 10 ，在碳納米管負(fù)載系數(shù)（COP /碳納米管納米） 18 ，警察線加載對(duì)碳纖維布（警察/ CC） 20 ，和二硫化鉬裝載在介孔石墨烯泡沫（MoS2 / MGF） 24 。納米結(jié)構(gòu)的導(dǎo)電載體是眾所周知的，以提高催化劑的電子傳遞，因此，催化劑的性能 25 。帶電性質(zhì)的有限和P電子納米棒是類似的氫受體和質(zhì)子受體Ni2P催化劑，鎳鐵氫化酶，和它的類似物，這可以解釋的電子納米棒的高效催化活性。Materials and methods 實(shí)驗(yàn)材料與方法Synthesis of Co2P nanorods對(duì)Co2P納米棒的合成

19、Cobalt acetate tetrahydrate(0.50g,2mmol) was mixed with oleylamine (12g,45mmol) in a 100mL round-bottom flask. The flask was heated via a heating mantle. A dispersion was obtained by stirring the mixture at 70 1C. The dispersion was then heated to 120 1C and triphenylphosphine (5.246g,20mmol) was ad

20、ded to the mixture. The flask was pumped under vacuum at 120 1C for30min to remove water, and then refilled with N2. The temperature of the heating mantle was increased to 370 1C and maintained at this value for 10 min. The flask was removed from the heating mantle and cooled to room temperature. Th

21、e black product was isolated and washed by repeated centrifugation/ultrasonication, with hexane as good solvent and ethanol as non-solvent. Finally, the product was dried under vacuum at room temperature.四水合醋酸鈷（0.50g，2mmol）混合油胺（12g，45mmol）在100mL圓底瓶中。燒瓶通過(guò)加熱罩加熱。攪拌，在70得到的分散。 分散加熱至120 1C和三苯基膦（5.246g，20）

22、混合。燒瓶抽真空在12030min至去除水分，然后再充滿N2。加熱罩的溫度 上升到370 1C，并且維持在這個(gè)溫度10 min。燒瓶被調(diào)離加熱罩和冷卻到室溫。 黑色產(chǎn)品隔離以及重復(fù)離心/超聲波清洗，用正己烷作為溶劑和非溶劑提取好。最后，該產(chǎn)品是在室溫下進(jìn)行真空干燥。Characterization表征The morphology of the Co2P nanorods was assessed by transmission electron microscopy (TEM,200kV,JEM2100,JEOL) and scanning electron microscopy (SEM,

23、7001F,JEOL). The energy-dispersive X-ray spectroscopy (EDX) spectrum was recorded using a GENESIS 2000 XM 30T (EDXA) on a JEM 2100. For the TEM investigation, the Co2P nanorods were dispersed in hexane by ultrasonication. The dispersion was dropped onto a carbon-coated copper grid (300-mesh). The co

24、pper grid was then dried at 100 1C for 5min before the TEM characterization. Powder X-ray diffraction (XRD) patterns were collected using a D8 Advance diffractometer with graphite-monochromated Cu K radiation (=1.54178Å) . The X-ray photoelectron spectroscopy (XPS) experiments were carried out

25、on an ESCALAB250Xi System (ThermoFisher) equipped with a monochromatic Al K (1486. 6 eV) source and a concentric hemispherical energy analyzer. The binding energy C1 speak from surface adventitious carbon (284.8 eV) was adopted as a reference for the binding energy measurements.Co2P的納米棒的形態(tài)通過(guò)透射電子顯微鏡（

26、TEM、200kV，評(píng)估jem2100，JEOL）和掃描電子顯微鏡（SEM，7001f，JEOL）確定。能量色散X射線光譜儀（EDX）頻譜被記錄一個(gè)GENESIS 2000 XM 30T (EDXA) 在一個(gè)JEM 2100。對(duì)于TEM 調(diào)查，Co2P納米棒分散在正己烷中超聲分散。分散投到碳包覆銅網(wǎng)（300目）。銅網(wǎng)格然后100條件下被干燥 5min在做TEM表征之前。粉末X射線衍射（XRD）圖案使用D8 高級(jí)衍射與石墨單色器收集Cu K輻射波長(zhǎng)（= 1.54178Å）。X射線光電子能譜 （XPS）的實(shí)驗(yàn)是在一個(gè)escalab250xi系統(tǒng)進(jìn)行 （招聘）配備了單色鋁K（1486 6

27、eV）源和同心半球能量分析儀。 結(jié)合能從C1講表面不定碳 （284.8 eV）的結(jié)合能作為參考 測(cè)量。Electrochemical performance電化學(xué)性能Co2P nanorods (15mg) were dispersed in hexane(0.5mL) with the aid of an ultrasonic horn(2mmdiameter,130W, 60 min).The dispersion(17 L) was dropped onto a clean Tifoil (0.5cm2) and dried naturally. The Ti foil was poli

28、shed by sandpaper (7000 mesh),and then cleaned by acetone, ethanol, and de-ionized water(15 min each) prior to the drop-coating of the Co2P nanorods.Co2P（15mg）納米棒被分散在正己烷（0.5ml）中在超聲變幅桿（直徑2毫米，130W，60分鐘）幫助下。分散物（17L）滴到一個(gè)干凈的鈦箔（0.5cm2），并且自然晾干。鈦箔是用砂紙打磨（7000目），然后用丙酮、乙醇和去離子水（每15分鐘）清洗，在Co2P納米棒的滴涂之前。裝上鈦箔的Co2P納

29、米棒在450 5% H2N2中退火30分鐘，以除去表面配體。All electrochemical measurements were carried out with an electrochemical workstation(CHI 614D,CH Instrument)in a three-electrode configuration, with Co2P (loaded ontoTi foil) as a working electrode ,a graphite rod(6mmdiameter) as a counter electrode ,and a mercury/ mer

30、curous sulfate electrode(MSE) or mercury/mercury oxide electrode (MMO) as a reference electrode .The samples wereassembled into a homemade electrochemical cell ,with onlya defined area(0.07 cm2) of the front surface of thesample exposed to solution during the measurements .Thecounter electrode was s

31、eparated from the working chamberby a porous glass frit.所有的電化學(xué)測(cè)量都在電化學(xué)工作站(CHI 614D,CH Instrument)進(jìn)行三電極結(jié)構(gòu)，用Co2P（裝載在Ti箔）作為工作電極，石墨棒（6mm直徑）作為反電極，和汞/汞硫酸電極（MSE）或汞/氧化汞電極（MMO）作為參考電極。樣品組裝成一個(gè)自制的電化學(xué)電池，只有一個(gè)定義的區(qū)域（0.07平方厘米）在測(cè)試過(guò)程中暴露于溶液樣品的前表面。反電極與工作腔通過(guò)多孔玻璃粉分離。H2SO4 aqueous solution(0.5M)or KOH aqueous solution(1 M)w

32、as used for electrochemical measurements. The MSEwas used as the reference electrode in H2SO4 solution, andthe MMO was used in KOH solution. The solutions werepurged with high purity H2 (99.999%) for 30min prior toelectrochemical measurements. The reversible hydrogenevolution potential(RHE) was dete

33、rmined by the opencircuit potential of a clean Pt electrode in the solution ofinterest bubbledwithH2 (99.999%), being 0.694 V vs. MSEfor the 0.5M H2SO4 solution and 0.876 V vs. MMO for the1 M KOH solution. A potential measured with respect to theMSE electrode was therefore referenced to the RHE byad

34、ding a value of 0.694V for the measurements in the 0.5MH2SO4 solution, and a potential measured with respect tothe MMO electrode in the KOH solution was referenced tothe RHE by adding a value of 0.876V.硫酸水溶液（0.5M）或氫氧化鉀水溶液（1M）被用于電化學(xué)測(cè)量。MSE在硫酸溶液中作為參考電極，以及MMO被用在氫氧化鉀溶液中。在電化學(xué)測(cè)量前30min該溶液被高純度H2（99.999%）凈化?？?/p>

35、逆的析氫電位（RHE）是由冒出H2（99.999%）氣泡的溶液中測(cè)定的一個(gè)清潔的Pt電極的開路電位，一般是0.694 V vs. MSE為0.5M H2SO4溶液和0.876 V vs. MMO為1 M KOH溶液。因此，對(duì)于可逆析氫電位在0.5M H2SO4溶液中MSE電極的測(cè)量電位參考方面應(yīng)增加0.694V的測(cè)量值，并且在KOH溶液中MMO電極應(yīng)增加0.876V的測(cè)量值。The polarization curves of Co2P samples were measured at a sweep rate of 5mV/s in rigorously stirred solution (

36、1600 rpm).The uncompensated cell resistance (R) was determined by the current-interrupt method, and the experimental potential was corrected by subtracting ohmic drop (iR), where i is the current corresponding to the experimental potential. The apparent Tafel slope was derived from the iR-corrected

37、polarization curve by fitting experimental data to the equation =a+blogj, where is the iR-corrected potential, a is the Tafel constant, b is the Tafel slope, and j is the current density. Electrochemical impedance spectroscopy(EIS)measurements were carried out at different potentials in the frequenc

38、y range of 10 -2 to 10-6 Hz with 10mV sinusoidal perturbations and 12 steps per decade in0.5M H2SO4 solution.在嚴(yán)格的攪拌溶液中用5mV/s掃描速率測(cè)量Co2P樣品的極化曲線（1600轉(zhuǎn)）。未補(bǔ)償電阻（R）用電流中斷法確定，并且實(shí)驗(yàn)電位的校正是通過(guò)對(duì)應(yīng)的實(shí)驗(yàn)電位減去電阻電壓降（IR），i是對(duì)應(yīng)的實(shí)驗(yàn)電流。顯然塔菲爾斜率由iR校正極化曲線通過(guò)實(shí)驗(yàn)數(shù)據(jù)擬合方程= A + blogj導(dǎo)出，在這里是iR校正電位，a是塔菲爾常數(shù)，b是塔菲爾斜率，和j是電流密度。電化學(xué)阻抗譜（EIS）進(jìn)行了測(cè)量在不

39、同電位的10 2至10-6赫茲的頻率范圍，10mV的正弦擾動(dòng)和在0.5M H2SO4溶液每十年12步驟。For accelerated degradation investigations , cyclic vol-tammetric (CV) measurements were carried out with a 50 mV/s sweep rate between -0.240 and0.100V vs. RHE in the 0.5M H2SO4 solution, and -0.330 and0.080V vs. RHE in the 1 M KOH solution, withou

40、t accounting for uncompen sated resistance.為加速退化的調(diào)查，循環(huán)體積（CV）測(cè)量進(jìn)行50 mV/s速率的掃描在-0.240 和0.100v vs之間.在0.5M硫酸溶液之間進(jìn)行的RHE，并在0.330 和0.080v vs之間.在1M 氫氧化鉀溶液的RHE，沒有記錄 uncompen滿足電阻。The volume of H2 during a potentiostatic electrolysisexperiment was monitored by water displacement in aconfiguration shown in Figu

41、re S1 (Electronic supplementaryinformation). In this experiment , the backside of the Ti foilwas connected to a Cu wire with Ag paste. The Cu wire wasthreaded to a glass tube(6mmdiameter),and the backsideand front side of the sample electrode were then sealedwith epoxy resin with the exception of an

42、 exposed area(0.5 cm2). A Free scale MPXV7002DP differential pressuretransducer was employed to monitor pressure variation inthe gas gathering tube, and then the volume of generatedH2 was computed from pressure variation in the gas gathering tube(see details in Electronic supplementary information).

43、 The current and charge passing the Co2P nanorodswere measured with the electrochemical workstation andthe voltage change of the differential pressure transducerwas monitored with a digital multi meter (41/2digits).Priorto experiment, the relationship between the volume ofgathered gas and the variat

44、ion of the output voltage of thedifferential pressure transducer(i.e., pressure variation inthe gas gathering tube)was calibrated by injecting knownamounts of air into the gas gathering tube and recording thevariation of the output voltage of the differential pressuretransducer.恒電位電解實(shí)驗(yàn)中氫氣的體積是由圖S1所示配

45、置水位移監(jiān)測(cè)（電子補(bǔ)充資料）。在這個(gè)實(shí)驗(yàn)中，對(duì)鈦箔的背面是連接到一個(gè)與銀漿銅導(dǎo)線。銅導(dǎo)線穿過(guò)玻璃管（直徑6mm），并且樣品電極的背面和正面除暴露的區(qū)域外全部用環(huán)氧樹脂密封（0.5平方厘米）。一個(gè)自由的尺度MPXV7002DP差壓傳感器來(lái)監(jiān)測(cè)在集氣管壓力的變化，然后由氣體收集管的壓力變化計(jì)算出生成的H2的體積（電子輔助信息查看詳情）。Co2P納米棒的電流和電荷傳遞用電化學(xué)工作站測(cè)量并且差壓壓力傳感器的電壓變化是由數(shù)字多用表監(jiān)測(cè)（41 / 2digits）。實(shí)驗(yàn)前，收集到的氣體的體積和輸出電壓的變化之間的關(guān)系通過(guò)將已知量的空氣注入到氣體收集管中，并記錄差壓壓力傳感器輸出電壓的變化，對(duì)差壓壓力傳感器

46、（即氣體收集管中的壓力變化）進(jìn)行了標(biāo)定。Results and discussionThe HER performance of the Co2P nanorods was evaluated by polarization curve measurements(jV plots).Prior to measurements ,the Co2P nanorods were applied to Ti foils (loading amount ca.1mg/cm2) by drop coating, andAnnealed at 450 in a 5%H2/N2 atmosphere for

47、30 min toremove surface ligand 17. The measurements were carriedout in a 0.5M H2SO4 solution with a three-electrode configuration(see details in the Materials and methods section).Figure 4a shows the jV plots of the Co2P nanorods ,bare Tifoil, commercial Pt/C(Johnson Matthey, Hispec3000,20wt%)loaded

48、 on a glassy carbon electrode (GCE),and a bare GCE.It was verified that cobalt phosphate can be dissolved in the0.5 M H2SO4 solution (Figure S6, Electronic supplementaryinformation); therefore ,the cobalt phosphate present onthe surface of the Co2P nanorods would be dissolved andshould not affect th

49、e catalytic activity of the Co2P nanorodsduring the electrochemistry measurements. It can be seenthat the bare Ti foil exhibits negligible current flow in thepotential range of 250 to 0mV vs. RHE, suggesting thatthe current flow of the Co2P nanorods supported on the Tifoil sample in this potential r

50、ange is induced by the Co2Pnanorods, but not the Ti foil. The onset of current is foundat ca.- 70 mV vs. RHE for the Co2P nanorods. The 20 is167 mV for the Co2P nanorods, and the over potentialrequired for a current density of 10mA/cm2 (10) is134 mV. The 20 and 10 values of different catalysts areus

51、ually compared in order to evaluate their efficiencies, because in photoelectrochemical applications a photo-cathode produces a current flux of 1020 mA /cm 2 under1 sun of AM1.5 G illumination 3. The performance ofrepresentative HER catalysts is summarized in Table1. Itcan be seen that the 20 and 10

52、 values of the Co2P nanorodsin our experiments are larger than those of CoP nanoparti-cles 19, Ni2P nanoparticles 17, NiMo nanopowders 29,MoP nanoparticles 21,22, CoP/CC 20, CoP/CNT 18,Mo1Soy/rGO 10 and MoS2/MGF) 24, and smaller thanother listed catalysts. NiMo nanopowders degrade rapidlyin acidic c

53、ondition, rendering their exploitation problematic29. The conductive CC, CNT, rGO , or MGF in CoP/CC,CoP/CNT,Mo1Soy/rGO orMoS2/MGF enhance the HER performance of these composites, in contrast to the Co2P nanorods in our experiments which are loaded on the Ti foil. Thiscomparison demonstrates that th

54、e HER performance of theCo2P nanorods in our experiments compares favorably withmost values of recently reported high efficiency non-precious electrocatalysts.通過(guò)極化曲線測(cè)量評(píng)估了HER的電子納米棒的性能（JV圖）。測(cè)量前，Co2P納米棒用于鈦箔（裝載量約1mg/cm2）滴涂，退火在450在5% H2N2氣氛30分鐘去除表面配體 17 。測(cè)量是在一個(gè)有一三個(gè)電極配置0.5M H2SO4溶液中進(jìn)行（在部分的材料和方法查看詳情）。圖4a顯示

55、電子納米棒的JV圖，純鈦箔、商業(yè)Pt/C（Johnson Matthey，hispec3000,20wt %）裝在玻碳電極（GCE），與裸玻碳電極上。結(jié)果表明，磷酸鈷可以溶解在0.5 M H2SO4溶液（圖S6中，電子補(bǔ)充資料）；因此，在電化學(xué)測(cè)量過(guò)程中Co2P納米棒表面的磷酸鈷會(huì)溶解，不影響Co2P納米棒的催化活性?？梢钥闯?，裸Ti箔在250至0mV電位范圍電流可以忽略不計(jì)。首先，這表明支撐Co2P納米棒在Ti箔樣品在該電位范圍的電流是由Co2P納米棒的誘導(dǎo)，而不是鈦箔。目前被發(fā)現(xiàn)Co2P納米棒的RHE的開始電流大約是在70 mV vs。Co2P納米棒的20是167 mV，和在一個(gè)10mA/

56、cm2電流密度所需的過(guò)電位（10）為134 mV。不同催化劑的20和10值通常比較，以評(píng)估他們的效率，因?yàn)樵诠怆姂?yīng)用中一個(gè)光電陰極產(chǎn)生1020毫安/厘米2的電流密度在一個(gè)AM1.5 G的陽(yáng)光照明之下。HER催化劑的典型性能被總結(jié)在表1中?？梢钥闯?，在我們的實(shí)驗(yàn)中，Co2P納米棒的20和10值大于CoP納米粒 19 ， Ni2P納米粒 17 ，鎳鉬納米粉末 29 ，MoP納米粒21,22，CoP/CC 20 ，CoP / CNT 18 ，Mo1Soy/rGO 10 MoS2/MGF 24 ，小于其他上市的催化劑。鎳鉬粉末在酸性條件下迅速降解，補(bǔ)償他們的利用問(wèn)題 29 。導(dǎo)電的CC，CNT，RGO

57、，或MGF在CoP / CC，CoP /碳納米管，mo1soy / RGO ormos2 / MGF提高這些復(fù)合材料的HER性能，相比之下，在我們實(shí)驗(yàn)中是負(fù)載于鈦箔的Co2P納米棒。比較表明，HER在我們的實(shí)驗(yàn)中，Co2P納米棒性能可以媲美最近報(bào)道的價(jià)值最高的高效催化劑。High durability is of importance for a good electrocatalyst. The stability of the Co2P nanorods was evaluated by cyclic voltammetry (CV)sweeps between -0.240 and 0.

58、100 Vvs.RHE in the 0.5M H2SO4 solution. The corresponding jV curves of the CV sweeps(without iR correction)are shown in Figure4b. After 1000CV sweeps the 20 increases from181 to 194mV,the increase of the 20 being smaller than 15mV.The current density at 0 V vs.RHE in CV sweeps (2mA/ cm2, Figure4b) is larger than that in Figure 4a ( -0 mA/cm2). It is apparent that the larger current density is correlated with the faster scan rate(50mV/s)in CV sweeps, impl