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1.
Direct alcohol fuel cells (DAFCs) have attracted considerable research interest because of their potential application as alternative power sources for automotive systems and portable electronics. Pd-based catalysts represent one of the most popular catalysts for DAFCs due to their excellent electrocatalytic activities in alkaline electrolytes. Thus, it is of great importance to understand the structure-activity relationship of Pd electrocatalysts for alcohol electrocatalysis. Recently, size- and shape- controlled Pd nanocrystals have been successfully synthesized and subsequently used to study the size and shape effects of Pd electrocatalysts on alcohol electrocatalysis, in which the Pd (100) facet exhibited higher electrocatalytic oxidation activity for small alcohol molecules than the Pd (111) and (110) facets. Although it is well known that capping ligands, which are widely used in wet chemistry for the size- and shape-controlled synthesis of metal nanocrystals, likely chemisorb onto the surfaces of the resulting metal nanocrystals and influence their surface structure and surface-mediated properties, such as catalysis, this issue was not considered in previous studies of Pd nanocrystal electrocatalysts for electrocatalytic oxidation of small alcohol molecules. In this study, we prepared polyvinylpyrrolidone (PVP)-capped Pd nanocrystals with different morphologies and sizes and comparatively studied their electrocatalytic activities for methanol and ethanol oxidation in alkaline solutions. The chemisorbed PVP molecules transferred charge to the Pd nanocrystals, and the finer Pd nanocrystals had a higher coverage of chemisorbed PVP, and thus exposed fewer accessible surface sites, experienced more extensive PVP-to-Pd charge transfer, and were more negatively charged. The intrinsic electrocatalytic activity, represented by the electrochemical surface area (ECSA)-normalized electrocatalytic activity, of Pd nanocubes with exposed (100) facets increases with the particle size, indicating that the more negatively-charged Pd surface is less electrocatalytically active. The Pd nanocubes with average sizes between 12 and 19 nm are intrinsically more electrocatalytically active than commercial Pd black electrocatalysts, while the activity of Pd nanocubes with an averages size of 8 nm is less. This suggests that the enhancement effect of the exposed (100) facets surpasses the deteriorative effect of the negatively charged Pd surface for the Pd nanocubes with average sizes between 12 and 19 nm, whereas the deteriorative effect of the negatively charged Pd surface surpasses the enhancement effect of the exposed (100) facets for the Pd nanocubes with average sizes of 8 nm due to the extensive PVP-to-Pd charge transfer. Moreover, the Pd nanocubes with average sizes of 8 nm exhibit similar intrinsic electrocatalytic activity to the Pd nanooctahedra with (111) facets exposed and average sizes of 7 nm, indicating that the electronic structure of Pd electrocatalysts plays a more important role in influencing the electrocatalytic activity than the exposed facet. Since the chemisorbed PVP molecules block the surface sites on Pd nanocrystals that are accessible to the reactants, all Pd nanocrystals exhibit lower mass-normalized electrocatalytic activity than the Pd black electrocatalysts, and the mass-normalized electrocatalytic activity increases with the ECSA. These results clearly demonstrate that the size- and shape-dependent electrocatalytic activity of Pd nanocrystals capped with PVP for methanol and ethanol oxidation should be attributed to both the exposed facets of the Pd nanocrystals and the size-dependent electronic structures of the Pd nanocrystals resulting from the size-dependent PVP coverage and PVP-to-Pd charge transfer. Therefore, capping ligands on capped metal nanocrystals inevitably influence their surface structures and surface-mediated properties, which must be considered for a comprehensive understanding of the structure-activity relationship of capped metal nanocrystals. 相似文献
2.
Zhiyu Lin Yang Yang Mengsi Li Hao Huang Wei Hu Ling Cheng Wensheng Yan Zhiwu Yu Kaitian Mao Guoliang Xia Jian Lu Peng Jiang Kang Yang Ruirui Zhang Pengping Xu Changlai Wang Lin Hu Qianwang Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17129-17136
Graphene‐based materials still exhibit poor electrocatalytic activities for the hydrogen evolution reaction (HER) although they are considered to be the most promising electrocatalysts. We fabricated a graphene‐analogous material displaying exceptional activity towards the HER under acidic conditions with an overpotential (57 mV at 10 mA cm?2) and Tafel slope (44.6 mV dec?1) superior to previously reported graphene‐based materials, and even comparable to the state‐of‐the art Pt/C catalyst. X‐ray absorption near‐edge structure (XANES) and solid‐state NMR studies reveal that the distinct feature of its structure is dual graphitic‐N doping in a six‐membered carbon ring. Density functional theory (DFT) calculations show that the unique doped structure is beneficial for the activation of C?H bonds and to make the carbon atom bonded to two graphitic N atoms an active site for the HER. 相似文献
3.
Jianmin Yu Thi Anh Le Ngoc Quang Tran Prof. Hyoyoung Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6423-6436
The depletion of fossil fuels has accelerated the search for clean, sustainable, scalable, and environmentally friendly alternative energy sources. Hydrogen is a potential energy carrier because of its advantageous properties, and the electrolysis of water is considered as an efficient method for its industrial production. However, the high-energy conversion efficiency of electrochemical water splitting requires cost-effective and highly active electrocatalysts. Therefore, researchers have aimed to develop high-performance electrode materials based on non-precious and abundant transition metals for conversion devices. Moreover, to further reduce the cost and complexity in real-world applications, bifunctional catalysts that can be simultaneously active on both the anodic (i.e., oxygen evolution reaction, OER) and cathodic (i.e., hydrogen evolution reaction, HER) sides are economically and technically desirable. This Minireview focuses on the recent progress in transition-metal-based materials as bifunctional electrocatalysts, including several promising strategies to promote electrocatalytic activities for overall water splitting in alkaline media, such as chemical doping, defect (vacancy) engineering, phase engineering, facet engineering, and structure engineering. Finally, the potential for further developments in rational electrode materials design is also discussed. 相似文献
4.
《中国化学快报》2022,33(12):5158-5161
Understanding and establishing the structure-activity relation of nanoparticles is a prerequisite for rational design of high-performance electrocatalysts. Cu2O nanoparticles enclosed with different crystal facets, namely, o-Cu2O NPs with {111} facets, c-Cu2O NPs with {100} facets are prepared and their electrocatalytic properties for oxygen evolution reaction (OER) in alkaline condition are evaluated at single nanoparticle level with a combination of scanning electrochemical cell microscopy and scanning electron microscopy. It is found that the o-Cu2O NPs have significantly superior OER electrocatalytic activity compared to c-Cu2O, which is almost inert. The estimated turnover frequency (TOF) at 1.97 V vs. RHE on {111} facet increases from 4 s?1 to 115 s?1 with the octahedron edge length decreasing from 1.3 µm to 100 nm. Deposition of carbon on c-Cu2O surface barely promotes the activity, suggesting the inherent poor electric conductivity within the nanocrystal is most likely the reason for low activity. This work provides direct probing to single transition metal oxide crystals with dramatically different activity. 相似文献
5.
《Electrochemistry communications》2008,10(12):1909-1911
In this study, NiCu composite coatings were electrochemically deposited on a copper electrode (Cu/NiCu) and characterized by atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) techniques in view of their possible applications as electrocatalytic materials for the hydrogen evolution reaction (HER). The HER activity of the prepared electrodes were studied in 1 M KOH solution by cathodic current–potential curves and electrochemical impedance spectroscopy (EIS) techniques. It was found that, the NiCu coating has a porous structure and good electrocatalytic activity for the HER in alkaline medium. The HER activity of the Cu/NiCu electrode was higher than uncoated (Cu) and Ni coated (Cu/Ni) copper electrodes. Its catalytic activity was related to the porosity as well as synergistic interaction of Ni and Cu. 相似文献
6.
Platinum Multicubes Prepared by Ni2+‐Mediated Shape Evolution Exhibit High Electrocatalytic Activity for Oxygen Reduction 下载免费PDF全文
Liang Ma Dr. Chengming Wang Dr. Bao Yu Xia Keke Mao Jiawei He Prof. Xiaojun Wu Prof. Yujie Xiong Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2015,54(19):5666-5671
Pt(100) facets are generally considered less active for the oxygen reduction reaction (ORR). Reported herein is a unique Pt‐branched structure, a multicube, whose surface is mostly enclosed by {100} facets but contains high‐index facets at the small junction area between the adjacent cubic components. The synthesis is accomplished by a Ni2+‐mediated facet evolution from high‐index {311} to {100} facets on the frameworks of multipods. Despite the high {100} facet coverage, the Pt multicubes exhibit impressive ORR activity in terms of half‐wave potential and current density nearly to the level of the most active Pt‐based catalysts, while the durability of catalysts is well retained. The facet evolution creates a set of samples with tunable ratios of high‐index to low‐index facets. The results reveal that the excellent ORR performance of Pt multicubes is a combined result of active sites by high‐index facets and low resistance by flat surface. It is anticipated that this work will offer a new approach to facet‐controlled synthesis and ORR catalysts design. 相似文献
7.
Ting Ouyang Ya‐Qian Ye Chun‐Yan Wu Kang Xiao Zhao‐Qing Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4977-4982
Herein, we demonstrate the use of heterostructures comprised of Co/β‐Mo2C@N‐CNT hybrids for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline electrolyte. The Co can not only create a well‐defined heterointerface with β‐Mo2C but also overcomes the poor OER activity of β‐Mo2C, thus leading to enhanced electrocatalytic activity for HER and OER. DFT calculations further proved that cooperation between the N‐CNTs, Co, and β‐Mo2C results in lower energy barriers of intermediates and thus greatly enhances the HER and OER performance. This study not only provides a simple strategy for the construction of heterostructures with nonprecious metals, but also provides in‐depth insight into the HER and OER mechanism in alkaline solution. 相似文献
8.
Byeong Su Gu Dr. Soumen Dutta Yu-Rim Hong Dr. Odongo Francis Ngome Okello Hyeonae Im Seungil Ahn Prof. Dr. Si-Young Choi Prof. Dr. Jeong Woo Han Prof. Dr. Sunmin Ryu Prof. Dr. In Su Lee 《Angewandte Chemie (International ed. in English)》2023,62(31):e202307816
The performance of nanocrystal (NC) catalysts could be maximized by introducing rationally designed heterointerfaces formed by the facet- and spatio-specific modification with other materials of desired size and thickness. However, such heterointerfaces are limited in scope and synthetically challenging. Herein, we applied a wet chemistry method to tunably deposit Pd and Ni on the available surfaces of porous 2D−Pt nanodendrites (NDs). Using 2D silica nanoreactors to house the 2D-PtND, an 0.5-nm-thick epitaxial Pd or Ni layer ( e - Pd or e -Ni ) was exclusively formed on the flat {110} surface of 2D−Pt, while a non-epitaxial Pd or Ni layer ( n - Pd or n -Ni ) was typically deposited at the {111/100} edge in absence of nanoreactor. Notably, these differently located Pd/Pt and Ni/Pt heterointerfaces experienced distinct electronic effect to influence unequally in electrocatalytic synergy for hydrogen evolution reaction (HER). For instance, an enhanced H2 generation on the Pt{110} facet with 2D-2D interfaced e -Pd deposition and faster water dissociation on the edge-located n -Ni overpowered their facet-located counterparts in respective HER catalysis. Therefore, a feasible assembling of the valuable heterointerfaces in the optimal 2D n -Ni/e-Pd/Pt catalyst overcame the sluggish alkaline HER kinetics, with a catalytic activity 7.9 times higher than that of commercial Pt/C. 相似文献
9.
Ying Chen Wolfgang Schuhmann Achim Walter Hassel 《Electrochemistry communications》2009,11(10):2036-2039
The anisotropic electrocatalytic properties of gold nanobelts and nanoplates enclosed by either {1 1 0} or {1 1 1} facets were studied. Different strategies were used to synthesize these materials. It was found that the {1 1 0} surface of gold does not necessarily show a higher electrocatalytic activity than the {1 1 1} surface. The {1 1 0} surface of gold is more active than the {1 1 1} surface for glucose oxidation in both, neutral and alkaline media. However, for methanol oxidation in alkaline solution, the {1 1 0} surface shows a lower activity than the {1 1 1} surface, which is contrary to the general belief that {1 1 0} facet is the most active surface among the three basal planes. The possible mechanisms are discussed. 相似文献
10.
11.
《中国化学快报》2023,34(7):107788
Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic, which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution. Herein, the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS2 heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS2@h-NSC). Benefited from the synergistic effect of heterointerfacial Ru/RuS2, the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport, Ru/RuS2@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm2 for alkaline HER, outperforming most of the state-of-the-art catalysts. Further applying Ru/RuS2@h-NSC and its oxidized derivate for the overall alkaline water splitting, the required cell voltage is much lower than that of the commercial Pt/C||RuO2 pair to achieve the same current density. Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications. 相似文献
12.
Dr. Ming Zhao Dr. Huilin Li Wei Li Junying Li Lingya Yi Dr. Weihua Hu Prof. Chang Ming Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(71):17091-17096
An Ru-doping strategy is reported to substantially improve both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic activity of Ni/Fe-based metal–organic framework (MOF) for overall water splitting. As-synthesized Ru-doped Ni/Fe MIL-53 MOF nanosheets grown on nickel foam (MIL-53(Ru-NiFe)@NF) afford HER and OER current density of 50 mA cm−2 at an overpotential of 62 and 210 mV, respectively, in alkaline solution with a nominal Ru loading of ≈110 μg cm−2. When using as both anodic and cathodic (pre-)catalyst, MIL-53(Ru-NiFe)@NF enables overall water splitting at a current density of 50 mA cm−2 for a cell voltage of 1.6 V without iR compensation, which is much superior to state-of-the-art RuO2-Pt/C-based electrolyzer. It is discovered that the Ru-doping considerably modulates the growth of MOF to form thin nanosheets, and enhances the intrinsic HER electrocatalytic activity by accelerating the sluggish Volmer step and improving the intermediate oxygen adsorption for increased OER catalytic activity. 相似文献
13.
The hydrogen evolution reaction (HER) of water with metallic aluminum-based materials provides an important way to address the global energy challenge; however, fundamental mechanism and reaction dynamics governing the chemical and electronic properties remain a debated research topic. Here we further study the HER mechanisms for water splitting on typical 13-atoms clusters, Al12Ga and Al13, by first-principles DFT calculations. We noted that the doping of a Ga atom into the Al13 cluster could reduce the transition state barrier for H2O dissociation on the metal cluster. Furthermore, it is interesting that the second water molecule prefers to adsorb on the same metal site giving rise to both thermodynamically and kinetically favorable reaction pathways. Based on the well-established complementary active sites (CAS) mechanism for metal cluster reactivity, we provide insights into the reaction dynamics of such metal clusters with two water molecules, which also sheds light on the Eley-Rideal and Langmuir-Hinshelwood mechanisms in surface science. Natural bond orbitals (NBO) analysis was conducted to evaluate the donor-acceptor charge-transfer interactions between the cluster and the nucleophilic reagent. These results gain a better understanding of the mechanism for water reacting with aluminum-based materials. 相似文献
14.
Erping Cao Prof. Zhimin Chen Dr. Hao Wu Dr. Peng Yu Ying Wang Fei Xiao Shuo Chen Dr. Shichao Du Prof. Ying Xie Prof. Yiqun Wu Prof. Zhiyu Ren 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):4183-4189
Even though transition-metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)-modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B-CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm−2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics. 相似文献
15.
Erping Cao Zhimin Chen Hao Wu Peng Yu Ying Wang Fei Xiao Shuo Chen Shichao Du Ying Xie Yiqun Wu Zhiyu Ren 《Angewandte Chemie (International ed. in English)》2020,59(10):4154-4160
Even though transition‐metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)‐modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B‐CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm?2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics. 相似文献
16.
Xiaoxia Chen Xiangjun Zhen Hongyu Gong Le Li Jianwei Xiao Zhi Xu Deyue Yan Guyu Xiao Ruizhi Yang 《中国化学快报》2019,30(3):681-685
Metal (cobalt)/nitrogen codoped carbon was first fabricated by pyrolysis of coordinated “noncarbonizable” polymer as bifunctional catalyst for ORR and HER, which showed better electrocatalytic performances than most bifunctional doped carbon catalysts in alkaline electrolyte. 相似文献
17.
Yan Zhang Fei Ye Wei-Dong Z. Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3766-3771
The development of high-efficiency bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline surroundings is essential and challenging for the large-scale generation of clean hydrogen. Herein, a novel self-assembled two-dimensional (2 D) NiO/CeO2 heterostructure (HS) consisting of NiO and CeO2 nanocrystals is prepared through a facile two-step approach, and utilized as an enhanced bifunctional electrocatalyst for the HER and OER under alkaline conditions. It is concluded that this 2 D NiO/CeO2 HS, rich in oxygen vacancies, demonstrates attractive electrocatalytic properties for both the HER and OER in 1 m KOH, including low onset overpotential (η1), η10 and Tafel slope, excellent durability, as well as large active surface area. Therefore, the self-assembled 2 D NiO/CeO2 HS is believed to be an efficient bifunctional electrocatalyst toward the HER and OER. 相似文献
18.
Alejandra Medrano-Banda Dr. Alfonso Crespo-Yapur Dr. Miguel Ángel Velasco-Soto Dr. Marcelo Videa 《ChemistryOpen》2022,11(2):e202100241
The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H2 generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (ΓNi) and Pt (ΓPt) were calculated from electrochemical measurements; the ΓPt/ΓNi ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A gPt−1, which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods. 相似文献
19.
《中国化学快报》2021,32(11):3591-3595
Crystalline engineering and heterostructure have attracted much attention as effective strategies to improve the electrocatalytic activity for hydrogen evolution reaction (HER). In this study, a new heterostructure catalyst (Ru/RuS2@N-rGO) with low crystallinity was fabricated by a simple and low-temperature method for HER in alkaline solution, applying the Na2SO4 as S source and polypyrrole as N source. Optimizing through the controllable crystalline engineering and composition ratio of Ru and RuS2, the Ru/RuS2@N-rGO heterocatalyst at the calcining 500 °C revealed highly efficient HER activity with overpotential 18 mV at a current density 10 mA/cm2 and remarkable stability for 24 h in 1.0 mol/L KOH. This work provides a facile and effective method in designing advanced electrocatalysts for HER in the alkaline electrolytes by synergistically structural and component modulations. 相似文献
20.
Ultrathin WS2 Nanoflakes as a High‐Performance Electrocatalyst for the Hydrogen Evolution Reaction 下载免费PDF全文
Dr. Liang Cheng Wenjing Huang Qiufang Gong Changhai Liu Prof. Zhuang Liu Prof. Yanguang Li Prof. Hongjie Dai 《Angewandte Chemie (International ed. in English)》2014,53(30):7860-7863
Much has been done to search for highly efficient and inexpensive electrocatalysts for the hydrogen evolution reaction (HER), which is critical to a range of electrochemical and photoelectrochemical processes. A new, high‐temperature solution‐phase method for the synthesis of ultrathin WS2 nanoflakes is now reported. The resulting product possesses monolayer thickness with dimensions in the nanometer range and abundant edges. These favorable structural features render the WS2 nanoflakes highly active and durable catalysts for the HER in acids. The catalyst exhibits a small HER overpotential of approximately 100 mV and a Tafel slope of 48 mV/decade. These ultrathin WS2 nanoflakes represent an attractive alternative to the precious platinum benchmark catalyst and rival MoS2 materials that have recently been heavily scrutinized for the electrocatalytic HER. 相似文献