CuPt and CuPtRu Nanostructures for Ammonia Oxidation Reaction

Manso, Ryan H.; Song, Lihong; Liang, Zhixiu; Wang, Jia X.; Chen, Jingyi

doi:10.1149/08512.0177ecst

Cited by 9 publications

(4 citation statements)

References 8 publications

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“…Overall, the AOR activity of the best-performing (100) Pt 85 Pd 15 /rGO ( E onset : 0.467 V and J p : 164.9 A g –1 ), regarded as the optimal PtPd catalyst in this work, is superior or comparable to those reported in the literature ,,,− (Table S5), such as the Pt-based binary catalysts (e.g., PtEu/C, E onset : 0.477 V and J p : 142.8 A g –1 ) or the carbon-supported Pt nanocubes (e.g., Pt NC/C, E onset : 0.480 V, and J p : 190 A g –1 ).…”

Section: Resultssupporting

confidence: 55%

Surface Structure Engineering of PtPd Nanoparticles for Boosting Ammonia Oxidation Electrocatalysis

Liu

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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Achieving high catalytic ammonia oxidation reaction (AOR) performance of Pt-based catalysts is of paramount significance for the development of direct ammonia fuel cells (DAFCs). However, the high energy barrier of dehydrogenation of *NH2 to *NH and easy deactivation by *N on the Pt surface make the AOR show sluggish kinetics. Here, we have put forward an alloying and surface modulation tactic to optimize Pt catalysts. Several spherical PtM (M = Co, Ni, Cu, and Pd) binary nanoparticles were controllably loaded on reduced graphene oxide (rGO). Among others, spherical PtPd nanoparticles displayed the most efficient catalytic activity. Further surface engineering of PtPd nanoparticles with a cubic-dominant structure has resulted in dramatic AOR activity improvements. The optimized (100)Pt85Pd15/rGO exhibited a low onset potential (0.467 V vs reversible hydrogen electrode (RHE)) and high peak mass activity (164.9 A g–1), much better than commercial Pt/C. Nevertheless, a short-term stability test along with morphology, structure, and composition characterizations indicate that the leaching of Pd atoms from PtPd alloy nanoparticles, their structure transformations, and the possible poisoning effects by the N-containing intermediates could result in the catalyst’s activity loss during the AOR electrocatalysis. A temperature-dependent electrochemical test confirmed a reduced activation energy (∼12 kJ mol–1 decrease) of cubic-dominant PtPd compared to Pt/C. Density functional theory calculations further demonstrated that Pd atoms in Pt decrease the reaction energy barrier of electrochemical dehydrogenation of *NH2 to *NH, resulting in an excellent catalytic activity for the AOR.

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Section: Resultssupporting

confidence: 55%

Surface Structure Engineering of PtPd Nanoparticles for Boosting Ammonia Oxidation Electrocatalysis

Liu

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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“…Overall, the AOR activity of the optimal PtIrNi 1 /SiO 2 -CNT-COOH catalyst (∼0.40 V onset potential, peak current density 124.0 A g −1 ) is superior or comparable to those of many reported catalysts, such as the CeO 2 -modified Pt catalyst (onset potential: ∼0.50 V), 37 Pt-decorated highly porous flowerlike Ni particles (onset potential: ∼0.50 V), 24 PtIr/CNT (atomic ratio of Pt/Ir = 4:1, onset potential: ∼0.38 V), 56 PtIr/ N-reduced graphene oxide (rGO) (molar ratio of Pt/Ir = 1:3, onset potential: ∼0.37 V), 27 PtRh/C (molar ratio of Pt/Rh = 9:1, onset potential: ∼0.44 V), 25 CuPtRh nanowires (mass ratio of Pt/Ru = 7:1, onset potential: ∼0.49 V), 57 and PtIrZn (mass ratio of Pt/Ir = 8:2, onset potential: ∼0.30 V). 33 Detailed comparisons in terms of onset potential and/or peak current density can be found in Table S4.…”

Section: Resultsmentioning

confidence: 99%

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

Pillai

et al. 2020

ACS Catal.

139

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Ammonia (NH3) has proved to be an effective alternative to hydrogen in low-temperature fuel cells via its direct ammonia oxidation reaction (AOR). However, the kinetically sluggish AOR has prohibitively hindered the attractive direct ammonia fuel cell (DAFC) applications. Here, we report an efficient AOR catalyst, in which ternary PtIrNi alloy nanoparticles well dispersed on a binary composite support consisting of porous silicon dioxide (SiO2) and carboxyl-functionalized carbon nanotube (PtIrNi/SiO2-CNT-COOH) through a sonochemical-assisted synthesis method. The PtIrNi alloy nanoparticles, with the aid of abundant OHad provided by porous SiO2 and the improved electrical conductivity by CNTs, exhibit remarkable catalytic activity for the AOR in alkaline media. It is evidenced by a lower onset potential (∼0.40 V vs reversible hydrogen electrode (RHE)) at room temperature than that of commercial PtIr/C (ca. 0.43 V vs RHE). Increasing NH3 concentrations and operation temperatures can significantly enhance AOR activity of this PtIrNi nanoparticle catalyst. Specifically, the catalyst at the temperature of 80 °C exhibits a much lower onset potential (∼0.32 V vs RHE) and a higher peak current density, indicating that DAFCs operated at a higher temperature are favorable for increased performance. Constant-potential density functional theory (DFT) calculations showed that the Pt–Ir ensembles on {100}-terminated surfaces serve as the active site. The introduction of Ni raises the center energy of the density of states projected onto the group d-orbitals of surface sites and thus lowers the theoretical onset potential for *NH2 dehydrogenation to *NH compared to Pt and Pt3Ir alloy.

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“…Ru, Pd, and Rh had little to no consistent AOR activity as evidenced by transient N 2 production, while the coinage metals exhibited electrodissolution in the presence of ammonia and no faradaic current. This study paved the way for further in-depth studies on Pt and Ir as well as bimetallic − and trimetallic systems. − Experimental studies on pure Pt demonstrate that it has an AOR onset potential of around 0.7 V RHE , and the reaction occurs primarily on the (100) facet . Despite the selectivity of Pt toward N 2 formation, it was found that adsorbed N and NO x species deactivate the catalyst surface; thus, there have been efforts to alloy Pt with other transition metals in binary , and ternary mixtures , as well as to modify the Pt surface with rare earth oxides. , …”

Section: Introductionmentioning

confidence: 99%

Favorable Electrocatalytic Ammonia Oxidation Reaction Thermodynamics on the β-NiOOH(0001) Surface Computed by Density Functional Theory

Choueiri

Chen

2022

J. Phys. Chem. C

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The electrocatalyzed ammonia oxidation reaction (AOR) is an ambient temperature and pressure process with potential applications for sustainable energy generation and waste ammonia treatment. In this work, we study the mechanism of ammonia oxidation toward N2, NO2 –, and NO3 – on the (0001)β-NiOOH surface and compare the computed free energy of reaction intermediates to results previously obtained on (0001) β-Ni(OH)2. NiOOH surfaces with a hydroxide vacancy favored NH2–NH2 coupling and reduced the theoretical onset potential for N2, NO2 –, and NO3 – formation relative to the β-Ni(OH)2 surface. The surface with an oxygen vacancy favored NH–NH coupling and had lower onset potentials for N2 and NO2 – formation relative to the β-Ni(OH)2 surface, while NO3 – formation was slightly hindered due to its increased stabilization of the precursor adsorbate, *NO2. In general, the NiOOH surface had lower computed onset potentials compared to the Ni(OH)2 surface due to the destabilization of certain adsorbates which form thermodynamic sinks in the AOR pathway, leading to differences in the potential-determining step for the formation of N2 and NO2 –.

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CuPt and CuPtRu Nanostructures for Ammonia Oxidation Reaction

Cited by 9 publications

References 8 publications

Surface Structure Engineering of PtPd Nanoparticles for Boosting Ammonia Oxidation Electrocatalysis

Surface Structure Engineering of PtPd Nanoparticles for Boosting Ammonia Oxidation Electrocatalysis

Ternary PtIrNi Catalysts for Efficient Electrochemical Ammonia Oxidation

Favorable Electrocatalytic Ammonia Oxidation Reaction Thermodynamics on the β-NiOOH(0001) Surface Computed by Density Functional Theory

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