Pt Core@ multishell Nanowires with

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Engineering Spiny PtFePd@PtFe/Pt Core@multishell Nanowires with Enhanced Performance for Alcohols Electrooxidation Yangping Zhang, Fei Gao, Caiqin Wang, Yukihide Shiraishi, and Yukou Du ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.9b09110 • Publication Date (Web): 01 Aug 2019 Downloaded from pubs.acs.org on August 4, 2019

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ACS Applied Materials & Interfaces

Engineering Spiny PtFePd@PtFe/Pt Core@multishell Nanowires with Enhanced Performance for Alcohols Electrooxidation

Yangping Zhang†, Fei Gao†, Caiqin Wang* ‡, Yukihide Shiraishi§, Yukou Du*†

† College

of Chemistry, Chemical Engineering and Materials Science, Soochow

University, 199 Renai Road, Suzhou 215123, P.R. China ‡College of Science, Nanjing Forestry University, 159 Longpan Road, Nanjing, 210037, P.R. China § Tokyo University of Science Yamaguchi, Sanyo-Onoda-shi, Yamaguchi 756-0884, Japan

* Corresponding author: * Yukou Du, E-mail: [email protected]. * Caiqin Wang, E-mail: [email protected]

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ABSTRACT Engineering robust electrocatalysts is always a key point in direct alcohols fuel cells (DAFCs). Catalysts with one-dimension (1D) structure are well studied and considered as promising candidates among various catalysts in the past decades, however, the precise regulation on the surface structure of 1D nanomaterials is still a worthy subject. By creatively introducing trimetallic nanoalloy, core@multishell structure, and 1D nanowire morphology, we have constructed a kind of novel spiny PtFePd@PtFe/Pt core@multishell 1D nanowires (NWs) catalysts with PtFePd as core and PtFe/Pt as multishell on the basis of improving catalytic property. The compositionoptimized Pt5FePd2 1D NWs display remarkable catalytic properties for ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR), which mass activity are 4.965 and 4.038 A mg-1, 4.6 and 5.0, 4.0 and 9.2-fold higher than Pt/C and Pd/C catalysts. Furthermore, the obtained Pt5FePd2 NWs can also retain favorable stability after durability tests. The unique core@multishell structure, spiny 1D NWs with many steps and kinks, and interior electronic and synergistic effect all contribute to the advanced catalytic performance. The present work has rationally designed novel 1D PtFePd@PtFe/Pt core@multishell NWs catalysts and offers a meaningful guideline for the designing of high-performance electrocatalysts.

KEYWORDS: direct alcohol fuel cells, core@multishell, 1D nanowires, ethanol oxidation reaction, methanol oxidation reaction.


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INTRODUCTION Direct alcohols fuel cells (DAFCs) with high energy density, environment friendliness, and convenient transport and storage, have received extensive scientific attentions in recent years, particularly for direct ethanol fuel cells (DEFCs) and direct methanol fuel cells (DMFCs).1-4 However, searching for high-performance catalysts has been regarded as one of the key factors that hindering the practical application of DAFCs.5-7 Noble metal Pt and Pd have been considered as the most efficient catalysts, nevertheless, their low toxicity resistance for CO-like intermediate species, and exorbitant price impeded further development in DAFCs.8-10 Driven by this, it is worthwhile to design rational strategies to fabricate cost-effective Pt- and Pd-based nanocatalysts.11-14 It is reported that various approaches have been taken to prepare nanocatalysts with optimized performance. One reliable and efficient strategy is constructing of onedimensional (1D) nanostructure.15-17 There are lots of studies on 1D nanowires (NWs), most of them exhibit smooth surface and limited performance, hence the precise fabrication of 1D NWs with many kinks and irregular interface on the consideration of promoted electrocatalytic behaviors is desirable.18-20 In view of this, 1D NWs with many steps and kinks are favorable to provide more active areas, facilitate electron transfer, and boost the coupling between nanomaterials and catalytic support, which appeals as a potential candidate among nanostructures.21-23 In addition, creating core@shell structures is another successful method for maximized catalytic activity.2426

Catalysts with core@shell structure are confirmed to display enhanced catalytic 3 ACS Paragon Plus Environment


activity in alcohols oxidation due to intrinsic closer lattice match, electronic and geometric effects, particularly for core@multishell structure, which is rarely investigated.27-29 Meanwhile, doping other non-noble metals in Pt or Pd to form alloy catalysts is still a mostly-used and effective technique for improved utilization of Pt and Pd.30-32 In nanoalloy catalysts, ternary nanocystals are proven to be satisfactory catalysts and exhibit superior catalytic activity and durability on account of well-tuned electronic, ligand, and interface strain effects.33,34 For example, Huang and co-workers demonstrated the as-synthesized trimetallic PtSnRh wavy NWs catalysts display favorable alcohols oxidation behavior, which is better than corresponding bimetallic PtSn catalysts.35 With this in mind, the exploration and optimization of ternary nanocatalysts on the catalysis in alcohols oxidation reactions are still desirable.36-39 In this work, we integrate the benefits of the above approaches, trimetallic nanoalloys, core@multishell construction, and kink-rich 1D nanowire structure, thus design a simple yet efficient method to construct PtFePd@PtFe/Pt core@muitishell nanowires with PtFePd as core and PtFe/Pt as multishell. Pt5FePd2 NWs, Pt5FePd3 NWs and Pt5FePd1 NWs were prepared by varying the amount of precursor Pd. The component-optimized Pt5FePd2 NWs exhibit the best electrocatalytic behaviors for ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR). The mass activity greatly exceeds the Pt5FePd3 NWs, Pt5FePd1 NWs, Pt/C, and Pd/C nanocatalysts. Meanwhile, Pt5FePd2 NWs are more steady than Pt/C and Pd/C catalysts after durability tests towards EOR and MOR under alkaline condition. It is believed the 4 ACS Paragon Plus Environment

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study will pave a way for further investigations on 1 D core@shell nanostructure catalysts with superior performance and so forth.

RESULTS AND DISCUSSION A kind of spiny PtFePd@PtFe/Pt core@multishell NWs was synthesized by an effective method (see the detailed information in Experimental Section and Figure S1).

Figure 1. Physical characterization of Pt5FePd2 NWs: (a, b) TEM images, (c) HRTEM image, (d) EDS line-scan profile (along the inset red arrow), (e) HAADF-STEM image and corresponding compositional mapping images, (f) XRD pattern, (g) SEM-EDS spectrum, (h) XPS spectra of survey scan. The morphology characterization of obtained Pt5FePd2 NWs was conducted via transmission electron microscopy (TEM) images. The products show a high yield and all display typical 1D architectures (Figure 1a). Specifically, each nanowire has a spiny and rough surface (Figure 1b), those bumps and pits on the skin of NWs make it easier 5 ACS Paragon Plus Environment


to provide abundant active sites, which is beneficial to the promotion of alcohols electrooxidation behaviors.40,41 Additional TEM image for structure and morphology of Pt5FePd2 NWs could be seen in Figure S2. The Pt5FePd2 NWs have a uniform distribution, whose mean length is 101.21 nm and mean diameter is 5.50 nm (Figure S3a and b). In the high-resolution TEM (HRTEM) image, the interplanar crystal spacing of nanowires is 0.226 nm, which is related to the {111} facet in face-centeredcubic (fcc) Pt and demonstrate the formation of Pt shell (Figure 1c). Furthermore, steps and kinks could be seen on the skin of Pt5FePd2 NWs that are beneficial for the enhancement of catalytic behaviors. The internal structure of nanowires was uncovered by line-scan analysis (Figure 1d), which demonstrated that the Pt mainly distributed in the outer while Fe and Pd mainly distributed in the inner of NWs. Coupled with the EDS elemental mapping images (Figure 1e), it could be confirmed that PtFePd is the core and PtFe/Pt consist the multishell in the nanostructure of NWs. The phase structure of as-obtained catalysts was understood by X-ray powder diffraction (XRD) technique. Figure 1f displays that the diffraction peaks shifted positively compared with Pt (JCPDS no.04-0802), Pd (JCPDS no.46-1043), and PtFe (JCPDS no.29-0717), indicating the formation of alloy phase. EDS analysis was employed to explore the constituent of Pt, Fe, and Pd in Pt5FePd2 NWs. The atomic ratio of Pt, Fe, and Pd is 62.7/12.6/24.7 (Figure 1g). In Figure 1h, the elemental valence in Pt5FePd2 NWs was investigated by XPS. Pt and Pd are mainly existed in metallic state, binding energies of Pd 3d and Pt 4f have deviated, indicating the occurrence of charge transfer in metallic Pt5FePd2 nanocrystals (Figure S4).42 6 ACS Paragon Plus Environment

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Figure 2. (a, b) TEM images, (c) line scan profile (through the inset red arrow), (d) XRD pattern, (e) SEM-EDS spectrum, (f) HAADF-STEM image and compositional mappings of as-prepared Pt5FePd3 NWs. Similarly, Pt5FePd3 core@muitlshell NWs were also prepared for comparison by tuning the composition of precursor. From Figure 2a, the Pt5FePd3 NWs show obvious 7 ACS Paragon Plus Environment


nanowires structure while the average length of 97.23 nm and width of 7.68 nm (Figure S5). Each NW also has an uneven surface where full of thorn-like humps, some of them intertwine together. (Figure 2b). Line scanning results of Pt5FePd3 NWs demonstrate the existence of Pt shell, where Pd and Fe mainly distributes in the core of each nanowire (Figure 2c). XRD analysis of Pt5FePd3 NWs uncovered the presence of fcc alloy phase in NWs (Figure 2d). EDS analysis show the element composition of Pt, Fe, and Pd is 56.4/11.2/32.4 in NWs (Figure 2e). More characterization such as HAADFSTEM images and relative element mapping images could further confirm that formation of PtFe/Pt multishell and the existence of interior PtFePd alloy despite the change of metal precursor (Figure 2f). The surface state of Pt5FePd3 NWs was analyzed by XPS, displaying that the majority elements are in zero valent state and a few Pt are in oxidation state (Figure S6).


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Figure 3. Structure and phase characterization of Pt5FePd1 NWs: (a) TEM image (b) SEM-EDS spectrum, (c) XRD pattern, (d) HRTEM image, (e) line-scan profile over the red arrow, (f) HAADF-STEM image and relevant elemental mapping images. For Pt5FePd1 NWs, most of the products show representative spiny and irregular interface. Compared with the former two samples, the minority of Pt5FePd1 NWs have relative smooth thorn-like surface and irregular structure (Figure 3a), which the mean length and diameter is 79.86 and 5.85 nm (Figure S7). The molar ratio of Pt, Fe, and Pd is 71.5/14.3/14.2 in NWs (Figure 3b). XRD technique was also conducted to understand the phase structure of obtained products and confirmed the formation of alloy phase. 9 ACS Paragon Plus Environment


(Figure 3c). Combined with the HRTEM image, the crystalline property of Pt5FePd1 NWs could be analyzed specifically. The shown facet displays typical lattice fringes which the interplanar distance is 0.226 nm, same as Pt5FePd3 NWs, which indicates the formation of Pt skin whether the composition variation (Figure 3d and S8). XPS analysis was also operated to study the surface elemental states in Pt5FePd1 NWs (Figure S9), which demonstrates the shift of binding energy and the existence of metallic Pt in as-prepared catalysts. Furthermore, it could be confirmed that Pt5FePd1 NWs have core@multishell structure as well where the core is PtFePd alloy and multishell is PtFe/Pt compound in view of the line scanning profile and elemental mapping images (Figure 3e and f). To uncover the formation mechanism of Pt5FePd2 NWs, time-tracking experiments, XRD and EDS characterizations relating to the morphology and component change of the intermediates in different reaction times were conducted (Figure S10). At the first 0.5h, the obtained products consist of a mass of ultrafine NWs and a small amount of irregular nanoparticles (Figure S10a). When the reaction goes for 1h, the NWs are getting thicker and several bumps are grown on each NWs (Figure S10b). At 3h, some bumps have grown into spines on the surfaces of each NWs (Figure S10c). When the reaction prolongs for 5h, many tiny spines appear on the skin of NWs (Figure S10d). At 8h, the products have evolved into spiny NWs (Figure S10e) and generally grown into uniform spiny NWs (Figure S10f). In addition, the composition and phase variation of Pt5FePd2 NWs could be seen in Figure S10g and h. For ease of comparison, the content of Pt is fixed as 1. At 0.5 h, the typical diffraction peaks could 10 ACS Paragon Plus Environment

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be observed in XRD patterns and the atomic ratio of Pt/Fe is 1/0.37 in the absence of Pd, which also implied the formation of alloy phase. With the increase of reaction time and addition of Pd, the diffraction peaks shifted positively and the content of Pd underwent a rapid growth and gradually approached to a flat. The content of Fe decrease slowly and soon reached a balance when the atomic ratio of Pt/Fe/Pd was stable at 1/0.20/0.39, which revealed the detailed formation process of Pt5FePd2 NWs. In addition, a sequence of experimental variation involving metal precursors, glucose, W(CO)6, phloroglucinol, and CTAC have been studied to acquire the optimized reaction condition. In the absence of Fe(Ac)2 (Figure S11), the products are made of some irregular and agminated nanoparticles (NPs), barely show NWs morphology. Considering the effect of glucose, the products mostly display tenuous NWs structure while still exist some NPs (Figure S12a and b). In Figure S12c and d, the resultants consist of disordered bulks without the introduction of phloroglucinol. The products all show a wide range of NPs and hardly form typical spiny NWs in the absence of W(CO)6 (Figure S13a and b) and CTAC (Figure S13c and d). The experimental results demonstrated that the proper amount precursors and selective use of glucose, W(CO)6, CTAC, and phloroglucinol have a great and comprehensive impact on the construction of PtFePd@PtFe/Pt core@multishell NWs.



Figure 4. (a) CV tests of Pt5FePd2 NWs, Pt5FePd3 NWs, Pt5FePd1 NWs, Pt/C, and Pd/C catalysts operated in 1 M KOH solution. (b) CV curves of them tested in an electrolyte containing 1 M KOH and 1 M ethanol. (c) i-t tests of the five catalysts tested at -0.25 V. (d) EOR stability comparison of those catalysts for successive 250 cycles of CV curves. EOR and MOR were selected as model reactions to estimate the catalytic performance of obtained Pt5FePd2 catalysts, the Pt5FePd3, Pt5FePd1, Pt/C, and Pd/C catalysts were synthesized as references, all the catalysts were loaded on carbon for subsequent electrochemical measurements (Figure S14). For EOR measurements, the CV curves were recorded in 1 M KOH solution to measure ECSAs values (Figure 4a). ECSA values of Pt5FePd2, Pt5FePd3, and Pt5FePd1 NWs are measured as 30.4, 29.8, and 21.9 m2g-1, respectively (Figure S15). Pt5FePd2 NWs exhibit the highest ECSA values, which imply their favorable performance for alcohols oxidation. After that, the EOR 12 ACS Paragon Plus Environment

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catalytic activities of those catalysts was tested. The peaks located at around -0.3 V could be ascribed to the electrooxidation process of ethanol molecule and peaks at around -0.4 V could be attributed to further oxidation of some intermediate products (Figure 4b).43,44 Specifically, the Pt5FePd2 NWs display the best activity among the five catalysts, whose mass activity/specific activity is 4.965 A mg-1/16.33A cm-2, 1.20/1.06, 1.53/1.10, 4.58/6.26, 5.00/6.56 times higher than Pt5FePd3, Pt5FePd1, Pt/C, and Pd/C catalysts, respectively (Figure S16). The as-prepared Pt5FePd2 NWs show the most satisfactory activity, which is even much better than the catalysts in previouslysynthesized literatures. (Table S1).

Figure 5. (a) CV tests of Pt5FePd2 NWs, Pt5FePd3 NWs, Pt5FePd1 NWs, Pt/C, and Pd/C catalysts towards MOR. (b) Mass and specific activity of the tested catalysts. (c) i-t measurements of the five catalysts operated at -0.25 V. (d) Durability comparison of 13 ACS Paragon Plus Environment


tested catalysts toward MOR for consecutive CVs of 250 cycles. Durability is also another key factor affecting the electrocatalytic performance. The current-time (i-t) curves were recorded at the fixed potential of -0.25 V to evaluate the stability of as-prepared Pt5FePd2, Pt5FePd3, Pt5FePd1 Pt/C, and Pd/C catalysts. In Figure 4c, catalysts may dissolute or poisoned by some intermediate species and they all show an obvious tendency to decay in the beginning stage.45,46 After i-t tests, the composition-optimized Pt5FePd2 NWs have been confirmed as the most stable catalysts with the highest retained mass activity of 0.428 A mg-1, higher than Pt5FePd3 (0.257 A mg-1), Pt5FePd1 (0.155 A mg-1), Pt/C (0.012 A mg-1), and Pd/C (0.009 A mg-1) catalysts. Furthermore, successive CV tests of 250 cycles were also conducted for further evaluating the endurance of those catalysts. Similarly, the retained mass activity of the above five catalysts show the following sequence: Pt5FePd2 NWs (1.446 A mg-1) > Pt5FePd3 NWs (1.184 A mg-1) > Pt5FePd1 NWs (0.818 A mg-1) > Pt/C (0.241 A mg-1) > Pd/C (0.088 A mg-1). The Pt5FePd2 NWs could still keep the highest mass activity among those tested catalysts (Figure 4d). As for MOR, the variation trend of electrochemical performance for tested catalysts is similar as that towards EOR. In Figure 5a, two typical peaks located at the CV curves, where the forward peak could be corresponding to the methanol oxidation reaction and the backward peak might be attributed to the oxidation process of several middle products formed in MOR.47,48 Obviously, the mass activity of obtained catalysts are 4.038 A mg-1 for Pt5FePd2, 3.244 A mg-1 for Pt5FePd3, 2.215 A mg-1 for Pt5FePd1, 1.007 A mg-1 for Pt/C, 0.441 A mg-1 for Pd/C catalysts. Their specific activity obeys 14 ACS Paragon Plus Environment

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the similar order as that of mass activity, which is 13.28, 10.89, 10.11, 2.42, and 1.11 mA cm-2 for Pt5FePd2, Pt5FePd3, Pt5FePd1 Pt/C, and Pd/C catalysts, respectively (Figure 5b). Taking stability into consideration, i-t tests were hence performed at the fixed potential of -0.25 V for evaluation of long time endurance (Figure 5c). The mass activities of those catalysts are decreasing as the test time going. The Pt5FePd2 NWs show the least decay among tested catalysts, whose retained mass activity is 0.634 A mg-1, higher than Pt5FePd3 (0.574 A mg-1), Pt5FePd1 (0.417 A mg-1), Pt/C (0.023 A mg1),

and Pd/C (0.006 A mg-1). The result of consecutive CV tests of 250 cycles still

demonstrates the best stability of Pt5FePd2 NWs among PtFePd NWs (Figure 5d). Furthermore, the Pt5Fe nanocatalysts in the absence of Pd while keeping the other parameter same as Pt5FePd2 NWs catalysts were also prepared. In Figure S17a, Pt5Fe catalysts display 1D nanowires structure and selected for comparison. CV curves of Pt5FePd2 NWs, Pt5Fe NWs, and Pt/C catalysts were recorded to investigate their catalytic activity. The electrocatalytic activity of Pt5Fe NWs towards EOR and MOR reaches to 2.254 A mg-1 and 2.244 A mg-1 (Figure S17b and c). The mass activity is lower than that of the Pt5FePd2 NWs and higher than Pt/C catalysts, indicating the introduction of Pd and their interior synergistic effect are favorable for the substantial enhancement of electrocatalytic performances. After durability tests, the morphologies and structures variation of Pt5FePd2 NWs, Pt5FePd3 NWs, and Pt5FePd1 NWs catalysts were also analyzed by TEM technique (Figure S18a-c). The as-tested Pt5FePd2 NWs catalysts could mostly maintain their initial well-defined structures with negligible morphology change, which also indicates the favorable stability of Pt5FePd2 NWs 15 ACS Paragon Plus Environment


nanomaterials. Based on the above results and discussions, the composition-optimized Pt5FePd2 NWs could also be considered as one of the most promising catalysts for MOR (Table S2).

CONCLUSIONS In summary, we have fabricated a series of novel trimetallic PtFePd@PtFe/Pt core@multishell NWs via a simple yet effective method for the first time. By adjusting the amount of Pd(acac)2, three kinds of PtFePd NWs were prepared, where the ternary PtFePd made up the core and PtFe/Pt formed the multishell structure regardless of the variation of precursor composition. The composition-optimized Pt5FePd2 NWs display high catalytic activity and favorable stability in EOR and MOR process, which might be ascribed to many reasons: electronic and synergistic effect among ternary PtFePd alloy assist to improve catalytic activity, unique spiny and uneven surface structure helps to offer rich active sites for EOR and MOR, core@multishell and 1D structure conduce to the improvement of stability. Notably, the as-prepared PtFePd@PtFe/Pt core@multishell NWs could be considered as one of the most promising catalysts and the synthetic strategy could also be used for reference for other practical applications in fuel cells and beyond.

EXPERIMENTAL SECTION Materials and Chemicals Platinum(II) acetylacetonate (Pt(acac)2, 97%), palladium (II) acetylacetonate (Pd(acac)2, 99%), iron(II) acetate (Fe(Ac)2, reagent grade, 95%), and tungsten carbonyl 16 ACS Paragon Plus Environment

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(W(CO)6, 99%) came from Shanghai Macklin Biochemical Co. Ltd. Phloroglucinol anhydrous

(C6H6O3,

≥99%),

Oleylamine

(OAm,

80-90%),

and

N-

Hexadecyltrimethylammonium Chloride (CTAC, >97.0%) were bought from Aladdin Co. Ltd. Glucose (C6H12O6, 98%), ethanol (CH3CH2OH, 98%), cyclohexane (C6H12, 98%) were bought from Sinopharm Chemical Reagent Co. Ltd. Water (H2O, 18 MΩ/cm) used in the measurements was collected by passing by an ultra-pure purification system. Synthesis of Spiny PtFePd@PtFe/Pt NWs In the synthesis of Pt5FePd2 NWs, 1.7 mg of Fe(Ac)2, 10 mg of Pt(acac)2, 50 mg of glucose, 7 mg of phloroglucinol anhydrous, 32 mg of CTAC, 5 mg of W(CO)6, and 5 mL OAm were mingled into a 20 mL glass vial. The compound was ultrasonicated for about 90 minutes after the vail been capped. The compounds were then moved into an oil bath, which heated from indoor temperature and maintain at 453 K for 0.5h. After cooling for a due time, 3 mg of Pd(acac)2 dissolved in 0.5 mL OAm were pipetted dropwise to the above hybrid and kept at 453 K for additional 9.5 h. After the reaction, the resultants were obtained by centrifuging and purified by ethanol/cyclohexane solution repeatedly. The preparation of Pt5FePd3 NWs and Pt5FePd1 NWs were similar with Pt5FePd2 NWs, except that 4.5 mg Pd(acac)2 for Pt5FePd3 NWs and 1.5 mg Pd(acac)2 for Pt5FePd1 NWs. Physical Characterizations The samples dispersed in cyclohexane solution were dropped on the carbon-coated copper grids and dried at indoor temperature for transmission electron microscopy (TEM, operate voltage: 120 kV) analysis. HITACHI HT7700 technique was employed 17 ACS Paragon Plus Environment


to obtain low resolution TEM images. High Resolution TEM were operated to investigate the refined morphology and structures of as-prepared catalysts, which carried out by FEI Tecnai F20 TEM (acceleration voltage: 200 kV). The surface elemental distribution of products was investigated by Energy Dispersive X-ray spectroscopy (EDS, S-4700, Japan). X-ray photoelectron spectroscopy (XPS) were applied to analyze the chemical states. The crystal structure and properties of catalysts were studied on XRD analysis technique. Electrochemical Tests The EOR and MOR measurements were operated by electrochemical work station made by Chen Hua Instrumental Co., Ltd (CHI760E). An electrolytic cell with three electrodes was employed to test electrocatalytic properties. In the electrochemical tests, the glassy carbon electrode (GCE, diameter: 3.0 mm) was used as a working electrode, which should also be polished via alumina powder each time before catalytic tests. the reference electrode is saturated calomel electrode (SCE), and the counter electrode is platinum wire. The as-prepared catalysts were loaded on C (20Wt% Pt and Pd) and further dispersed in a homogenous solution with isopropanol and 5 μL Nafion to generate a homogeneous catalytic ink (0.1/0.2 mgPt+Pd/mL for EOR/MOR tests). To fabricate a catalyst-covered electrode, catalytic ink (5 μL) was pipetted dropwise onto the working electrode and dried naturally. To estimate to catalytic behavior of catalysts, the electrochemical active surface area (ECSA) were measured in 1 M KOH electrolyte. The cyclic voltammetry curves (CVs) ranging from -0.9 V to 0.3 V were recorded to evaluate EOR/MOR activity in 1 M KOH and 1 M ethanol/1 M methanol electrolyte. 18 ACS Paragon Plus Environment

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Subsequently, successive CV curves for 250 cycles, and current-time curves were also conducted to analyze electrocatalytic stability.

ASSOCIATED CONTENT The Supporting Information is available free of charge on the ACS Publications website. Size distribution histogram, XPS spectra, Additional TEM images, Formation mechanism, ECSA values, Mass and Specific Activities of samples, Comparison Tables of EOR and MOR performance.

AUTHOR INFORMATION Corresponding Author * Yukou Du, E-mail: [email protected] (Y.D.) * Caiqin Wang, E-mail: [email protected] (C.W.)

ORCID Yukou Du: 0000-0002-9161-1821 Caiqin Wang: 0000-0002-3910-6705

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT The authors thank the National Natural Science Foundation of China (Grant No. 51873136), Natural Science Foundation of the Jiangsu Higher Education Institutions of China (18KJA150008), the project of scientific and technologic infrastructure of Suzhou (SZS201708), Natural Science Foundation of Jiangsu Province (BK20181428). 19 ACS Paragon Plus Environment


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313x147mm (96 x 96 DPI)

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Pt Core@ multishell Nanowires with

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