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81.
《International Journal of Hydrogen Energy》2021,46(72):35550-35558
The exploration of efficient catalysts toward hydrogen evolution reaction (HER) is still an urgent task. In this paper, Ni/Mo/Cu/C and Ni/Mo/C electrode were obtained by conventional pulse voltammetry, which acted as cathode in microbial electrolysis cells (MECs). The prepared samples are analyzed using SEM, XRD, XPS and electrochemical analysis techniques. Results indicated that the Ni/Mo/Cu coating has a rough and globular structure and presents high current density, a lower Tafel slope of 23.9 mV/dec than 30 mV/dec of Pt, which exceeds the electrochemical activity of Pt electrode. Its remarkably enhanced electrocatalytic activity is attributed to the high surface area, high conductivity as well as synergistic interaction among Ni, Mo and Cu. 相似文献
82.
《International Journal of Hydrogen Energy》2021,46(61):31202-31215
Direct methanol fuel cells (DMFCs) had been attracted considerable attention for its advantages of high energy density, simplified systems and readily transportation and storage of methanol. However, the notoriously sluggish kinetics of methanol oxidation reaction (MOR) of the anode reaction, had greatly affected the commercialization of DMFCs. On one hand, Pt based catalyst are still the most effective MOR catalysts, while the high cost caused by the high loadings of electrocatalyst to compensate the low MOR activity impedes the wide accessible of DMFCs. In addition, the occurrence of catalyst poisoning owing to the strong interaction between Pt and carbon monoxide (CO) generated during the MOR processing, further leading to the fast decay in the performance and stability of MOR electrocatalysts. Two-dimensional (2D) Pt based nanostructures is regarded to be one promising and effective class of MOR electrocatalysts, and attracted much attention due to the high electron mobility, highly exposed active sites, and extraordinary thermal conduction. In this review, the mechanism of MOR was firstly introduced, and then the synthesis conditions, structure characteristics and methanol oxidation performances both in acidic and alkaline dielectric of 2D Pt based nanocatalysts were introduced. Subsequently, we briefly analyzed the structural characteristics of 2D Pt based nanocatalysts and their advantages, including the low platinum loadings, high specific surface area and majority of atomic active sites exposed. Finally, the opportunities and challenges for designing of advanced 2D Pt based nanocatalysts was proposed and discussed. 相似文献
83.
《International Journal of Hydrogen Energy》2021,46(55):28011-28020
Transition metal-based compounds, due to their excellent ORR catalytic performance under alkaline condition, have recently emerged as one of the most promising alternatives to noble metal-based ORR catalysts. It is worth noting that manganese oxide can take an unique advantage for decomposition of intermediate adsorption products H2O2 and can effectively reduce O2 to OH−. However, most research has focused on MnO2, while attention has rarely been paid to MnO catalysts. In addition, under high-temperature pyrolysis condition, MnO is the most stable manganese oxide but MnO nanoparticles easily agglomerate. Hence, it is very difficult to obtain well-dispersed and small-sized MnO nanoparticles. Herein, on the basis of pre-synthesizing uniformly distributed manganese complexes on the reduced graphene oxide (rGO), we innovatively prepare highly dispersed and small-sized MnO nanoparticles (~3.94 nm) via high-temperature pyrolysis, which are uniformly anchored on N-doped reduced graphene oxide (NrGO) as an efficient oxygen reduction electrocatalyst. The as-obtained MnO/NrGO (1050 °C) electrocatalyst achieves satisfactory onset potential (0.942 V) and half-wave potential (0.820 V) under alkaline condition. And the limiting current density is 4.17 mA cm−2, which is very close to that of Pt/C (20 wt%, JM). Meanwhile, MnO/NrGO (1050 °C) catalyst presents superior longstanding durability and methanol resistance than Pt/C (JM). This work indicates that high-temperature pyrolysis can improve the purity of manganese oxide, simultaneously the defects of NrGO can reduce particle size of MnO nanoparticles, which are greatly beneficial to improve ORR performance. This work provides a new idea for research of MnO catalysts for ORR in the future. 相似文献
84.
《International Journal of Hydrogen Energy》2021,46(56):28709-28718
In this work, the crystal structure and hydrogen storage properties of V35Ti30Cr25Fe10, V35Ti30Cr25Mn10, V30Ti30Cr25Fe10Nb5 and V35Ti30Cr25Fe5Mn5 BCC-type high entropy alloys have been investigated. It was found that high entropy promotes the formation of BCC phase while large atomic difference (δ) has the opposite effect. Among the four alloys, the V35Ti30Cr25Mn10 alloy shows the highest hydrogen absorption capacity while the V35Ti30Cr26Fe5Mn5 alloy exhibits the highest reversible capacity. The cause of the loss of desorption capacity is mainly due to the high stability of the hydrides. The higher room-temperature desorption capacity of the V35Ti30Cr25Fe5Mn5 alloy is due to higher hydrogen desorption pressure. After pumping at 400 °C, the hydrides can return to the original BCC structure with only a small expansion in the cell volume. 相似文献
85.
《International Journal of Hydrogen Energy》2021,46(80):40217-40238
The primary purpose of this work is to develop a novel model for comprehensively investigating the hydrogen storage performance under the framework of diffusion of hydrogen atoms through hydride layer. The proposed model is constructed upon perfectly mathematical-physical equations, by taking into account complicated multi-scale and multi-physics coupling actions. Importantly, three-dimensional numerical simulations are performed to explore the coupling effects of micro diffusion, mesoscopic permeation, and macroscopic fluid flow. An analytical approach accounting for the characteristics of reaction bed, particle, and crystal grain is presented as well. In addition, a parametric analysis is conducted to reveal that the hydride particle dimension, particle porosity, grain size, and diffusion coefficient of reacted layer have a significant effect on overall hydrogen storage performance, highlighting that grain size and hydrogen diffusion coefficient are vital factors that need to be considered for material preparation and design. 相似文献
86.
Yan Luo Zeming Tang Guiqiang Cao Da Bi David P. Trudgeon Adeline Loh Xiaohong Li Qingxue Lai Yanyu Liang 《International Journal of Hydrogen Energy》2021,46(2):1997-2006
Atomically dispersed transition metals anchored on N-doped carbon have been successfully developed as promising electrocatalysts for acidic oxygen reduction reaction (ORR). Nonetheless, how to introduce and construct single-atomic active sites is still a big challenge. Herein, a novel concave dodecahedron catalyst of N-doped carbon (FeCuNC) with well confined atomically dispersed bivalent Fe sites was facilely developed via a Cu-assisted induced strategy. The obtained catalyst delivered outstanding ORR performance in 0.5 M H2SO4 media with a half-wave potential (E1/2) of 0.82 V (vs reversible hydrogen electrode, RHE), stemming from the highly active bivalent Fe-Nx sites with sufficient exposure and accessibility guaranteed by the high specific surface area and curved surface. This work provides a simple but efficient metal-assisted induced strategy to tune the configurations of atomically dispersed active sites as well as microscopy structures of carbon matrix to develop promising PGM-free catalysts for proton exchange membrane fuel cell (PEMFC) applications. 相似文献
87.
Chunyu Zhang Guozhu Liu Bo Ning Shuairen Qian Danning Zheng Li Wang 《International Journal of Hydrogen Energy》2021,46(27):14277-14287
The electrochemical oxygen reduction reaction (ORR) via two-electron pathway is a sustainable way of producing hydrogen peroxide. Nanostructured carbon materials are proved to be effective catalysts for 2e? ORR. Herein, a series of mesoporous carbon with tunable nitrogen species and oxygen functional groups were synthesized by varying the added amount of dopamine hydrochloride as nitrogen and oxygen source. The modified catalysts exhibited higher content of pyrrolic-N and ether C–O groups which are confirmed by a series of characterization. Raman spectra and correlation analysis revealed that the increased proportion of defect sites in carbon materials are closely related to the introduced pyrrolic-N and ether C–O groups. And the rotating ring-disk electrode (RRDE) measurement carried out in 0.1 M KOH electrolyte showed the H2O2 selectivity increased with the content of defect sites. Among them, the optimized catalyst (NOC-6M) exhibited a selectivity of 95.2% and a potential of 0.71 V vs. RHE at ?1 mA cm?2. Moreover, NOC-6M possessed the high H2O2 production rate of 548.8 mmol gcat?1 h?1 with faradaic efficiency of 92.4% in a two-chamber H-cell. Further mechanistic analysis revealed that the introduction of pyrrolic-N and ether C–O are likely to improve the binding energy of the defect sites toward 1OOH intermediate, resulting in a more favorable 2e? ORR pathway for H2O2 production. 相似文献
88.
《International Journal of Hydrogen Energy》2021,46(58):30061-30078
A uniform solid product layer normally assumed in the shrinking-core model cannot predict the kinetic transition behavior of the H2 adsorption reactions. In this study, the concept of a uniform solid product layer has been replaced by that of the inward growth of solid products on the solid surface. A rate equation is established to calculate the inward growth of the solid product and was implemented into the shrinking-core model to calculate the H2 adsorption kinetics for various shapes of Mg-based materials. The prediction accuracy of the developed model is verified from the detailed experimental data. To account for the external gas diffusion around the particle and the intraparticle gas diffusion, an analytical equation is derived using the Thiele modulus method. This model can be used to analyze various kinetic aspects and to analyze the effect of change in the particle microstructure on intraparticle diffusion. 相似文献
89.
Deok-Hye Park Yo-Seob Kim Sang-Beom Han Woo-Jun Lee Hak-Joo Lee Yong-Soo Lee Sang-Hyun Moon Kyung-Won Park 《International Journal of Hydrogen Energy》2021,46(43):22499-22507
Electrochemical reactions such as the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and methanol oxidation reaction (MOR) are essential for energy conversion applications such as water electrolysis and fuel cells. Furthermore, Pt or Ir-related materials have been extensively utilized as electrocatalysts for the OER, ORR, and MOR. To reduce the utilization of precious metals, innovative catalyst structures should be proposed. Herein, we report a bi-metallic phosphide (Ni2P and PdP2) structure surrounded by graphitic carbon (Ni–Pd–P/C) with an enhanced electrochemical activity as compared to conventional electrocatalysts. Despite the low Pd content of 3 at%, Ni–Pd–P/C exhibits a low overpotential of 330 mV at 10 mA cm?2 in the OER, high specific activity (2.82 mA cm?2 at 0.8 V) for the ORR, and a high current density of 1.101 A mg?1 for the MOR. The superior electrochemical performance of Ni–Pd–P/C may be attributed to the synergistic effect of the bi-metallic phosphide structure and core-shell structure formed by graphitic carbon. 相似文献
90.
Dinabandhu Patra Ramakrishnan Ganesan Balaji Gopalan 《International Journal of Hydrogen Energy》2021,46(50):25486-25499
We report the catalytic enhancement of hydrogen generation by 1) in situ Fe (0) formed and 2) nitroarenes substrates during Fe3O4@Pd core-shell nanoparticles catalyzed tandem reaction. The active hydrogen species are generated in Pd shell, which either combine to form H2 gas or take part in relatively faster nitroarene reduction reaction. The rate of hydrogen generation from ammonia borane is dependent on the nitroarene substrate and is higher when 4-nitrophenol is used. This is due to the difference in ammonia borane adsorption on the surface of the catalyst. During recyclability, the H2 generation rate of 2 wt% Pd loaded samples is higher than other compositions. Such an enhancement has been attributed to the formation of Fe (0) via γ-FeOOH mediated by Pd species, presumably through Pd(OH)2. The electronic connection between Fe and Pd interface is thus shown to play an important role in the catalytic enhancement of the tandem reaction. 相似文献