Platinum nanoparticles loaded on pristine and boron oxide modified carbon nano-onions for enhanced ammonia electrooxidation in alkaline direct ammonia fuel cells

Sikeyi, Ludwe L.; Ntuli, Themba D.; Mongwe, Thomas H.; Maxakato, Nobanathi Wendy; Coville, Neil J.; Maubane‐Nkadimeng, Manoko S.

doi:10.1016/j.jelechem.2022.116411

Cited by 18 publications

(5 citation statements)

References 79 publications

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“…The energy released from these steps would contribute to facilitate the subsequent oxidation process by increasing the vibrational energy level of the adsorbates according to the "hot atom" mechanism. [43] In accordance with previous reports that the Pt (200) facet features the highest AOR activity among the crystal planes in fcc Pt, [11,24,44] introduction of Ni at the (220) facet leads to obvious electron accumulation around the adjacent Pt atoms with significantly increased electron densities (Figure 5f), corresponding to the dramatically reduced energy barrier of AOR. This clearly indicates a crystal facets effect that the electron redistribution upon heteroatom doping is highly dependent on the crystal planes.…”

Section: Resultssupporting

confidence: 90%

“…The energy released from these steps would contribute to facilitate the subsequent oxidation process by increasing the vibrational energy level of the adsorbates according to the “hot atom” mechanism. [ 43 ] In accordance with previous reports that the Pt (200) facet features the highest AOR activity among the crystal planes in fcc Pt, [ 11,24,44 ] the rate‐determining step (RDS) of the (200) facet for Pt 93 Mo 7 (0.18 eV) is lower than the Pt 93 Mo 7 (111) (0.22 eV) and Pt 93 Mo 7 (220) (0.22 eV) surfaces. Further Ni‐doping does not make a contribution to the intrinsic activity of the Pt 93 Mo 7 (200) facet, and the RDS and limiting potential remain unchanged (Figure 4b; Figure S14, Supporting Information).…”

Section: Resultssupporting

confidence: 89%

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Awakening (220) as One More Active Facet of PtMo Alloy via Single‐Atom Doping to Boost Ammonia Electrooxidation in Direct Ammonia Fuel Cell

Liu

Jiang

Wang

et al. 2023

Adv Funct Materials

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As the core of low‐temperature direct ammonia fuel cell (DAFC) technology, electrocatalytic ammonia oxidation reaction (AOR) has proven to be most active on platinum‐based catalysts. However, the AOR is extremely surface sensitive that only the Pt (200) facet exhibits high reaction activity, whereas other facets usually do not make contributions. Herein, the inert (220) surface of PtMo nano‐alloy is successfully awakened as one more active facet in addition to (200) via directional single‐atom Ni‐doping. The introduction of Ni triggers a targeted electron accumulation around Pt sites at the (220) facet that significantly reduces the AOR energy barrier while maintaining the activity of the (200) surface. With a greatly enlarged active surface, the Ni‐decorated PtMo catalyst exhibits a significantly facilitated AOR kinetics with a low onset potential of 0.49 V versus reversible hydrogen electrode and a superior peak current density of 94.96 A g−1 at 5 mV s−1. Notably, the DAFC equipped with such an electrocatalyst reaches a remarkable peak power density of 16.70 mW cm−2 at low temperatures. It is believed that this strategy sheds light on exploiting the intrinsic activity of Pt‐based electrocatalysts, and drives the low‐temperature DAFC technology to a more practical level.

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Section: Resultssupporting

confidence: 90%

“…The energy released from these steps would contribute to facilitate the subsequent oxidation process by increasing the vibrational energy level of the adsorbates according to the “hot atom” mechanism. [ 43 ] In accordance with previous reports that the Pt (200) facet features the highest AOR activity among the crystal planes in fcc Pt, [ 11,24,44 ] the rate‐determining step (RDS) of the (200) facet for Pt 93 Mo 7 (0.18 eV) is lower than the Pt 93 Mo 7 (111) (0.22 eV) and Pt 93 Mo 7 (220) (0.22 eV) surfaces. Further Ni‐doping does not make a contribution to the intrinsic activity of the Pt 93 Mo 7 (200) facet, and the RDS and limiting potential remain unchanged (Figure 4b; Figure S14, Supporting Information).…”

Section: Resultssupporting

confidence: 89%

Awakening (220) as One More Active Facet of PtMo Alloy via Single‐Atom Doping to Boost Ammonia Electrooxidation in Direct Ammonia Fuel Cell

Liu

Jiang

Wang

et al. 2023

Adv Funct Materials

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“…[ 22,27–29 ] In addition, ammonia fuel cells are also theoretically superior to their hydrogen‐based counterparts in terms of energy density and fuel storage facileness ( Figure ). [ 30,31 ] Compared with hydrogen fuel cells, the evolution of ammonia fuel cells is still in its initial stage. This is mainly because the anodic AOR is more complex and sluggish than the hydrogen oxidation reaction.…”

Section: Introductionmentioning

confidence: 99%

“…[22,[27][28][29] In addition, ammonia fuel cells are also theoretically superior to their hydrogen-based counterparts in terms of energy density and fuel storage facileness (Figure 1). [30,31] Compared with hydrogen fuel cells, the evolution…”

mentioning

confidence: 99%

Green Chemistry: Advanced Electrocatalysts and System Design for Ammonia Oxidation

et al. 2023

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Fossil fuels, including coal, petroleum, and natural gas, are still the main sources of energy supply in the world at present. [1,2] Their nonrenewable nature, however, determines that the total amount of these fossil fuels is limited, thus leading to the potential energy crisis. [3,4] This issue has given a strong impetus to the development of green, safe, and renewable energy supplies, such as wind, solar, and tide energy. [5][6][7][8] Although these novel energy sources are generally sustainable, their direct utilization is extremely difficult. For example, these green energy types, especially solar energy, commonly suffer high fluctuation, thus leading to the misalignment of electricity generation of these energies with the actual demand. [9] Therefore, it is very important to explore and exploit the optimal secondary energy carriers. Among the secondary energy carriers, hydrogen is one of the most economical and eco-friendly carriers due to its zero-carbon emission, abundance, high energy density (120 MJ kg À1 ), etc. [10][11][12] Due to the potential safety hazards in the storage and transportation of hydrogen gas, nevertheless, its practical utilization has great limitations. [13,14] To address these issues, it has been suggested to use methane or ammonia gas as the hydrogen carriers. [15][16][17][18] Methane has a wide range of resources and mature industrial processing technologies. Thermal catalytic decomposition of methane and steam reforming is the most mature technology of hydrogen generation in the industry currently. [19,20] However, the transportation and storage of methane remain problematic owing to its physical characteristics, which are similar to those of hydrogen. As a cost-effective hydrogen carrier, ammonia can turn into a liquid state at room temperature under moderate pressure (%8 bar), much milder than that hydrogen gas (690 bar and 15 °C). [10,21,22] Besides, the utilization of ammonia does not associate with greenhouse gas emissions. Moreover, the energy density of liquid ammonia (11.5 MJ kg À1 ) is also higher than that of liquid hydrogen (8.5 MJ kg À1 ). Moreover, the presence of ammonia can be easily detected even at a very low concentration of 1 ppm, allowing ammonia leaks to be assessed and dealt with in a timely manner. In addition, unlike hydrogen, ammonia is widely used and vastly produced (global production is 176 million tons a year) around the world in the pharmaceutical, fertilizer, and chemical industries. Consequently, the well-established and mature ammonia production-related infrastructure makes ammonia a viable energy source. [23][24][25][26] To utilize ammonia for energy applications, electrochemical ammonia oxidation reaction (AOR) is essential, either for hydrogen production via ammonia splitting or electricity generation via direct ammonia fuel cells (DAFCs), which are highly commercially promising. During operation, DAFCs just produce water and nitrogen gas. [22,[27][28][29] In addition, ammonia fuel cells are also theoretically superior to their hydrogen-based c...

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“…Herein, oxidised boron-nitrogen codoped carbon nano-onions (oxi-BNCNO) and electrochemically synthesised microscale branched copper clusters (CuC/oxi-BNCNO) were explored as electrocatalysts in the preparation of an electrochemical sensor for the determination of EFV in wastewater and pharmaceutical formulations. The interest in the zerodimensional, quasi-spherical and polyhedral fullerene-like carbon nano-onions arises due to their high electrical conductivity (≈ 71.8 µS), catalytic activity, large surface area, resistance to corrosion, low cytotoxicity, and their ability to form composites with other materials [29][30][31][32][33][34][35][36][37][38]. In addition, copper and its oxides have gained prominence as electrocatalysts in sensor fabrication due to their natural abundance, ease of preparation, relatively low cost, excellent electrical conductivity and electrocatalytic activity, large surface area and good reproducibility [39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Copper-Modified Carbon Nano-Onions as Electrode Modifiers for the Electroanalysis of the Antiretroviral Drug Efavirenz

Mokwebo

Murphy

Guin

et al. 2023

Preprint

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Platinum nanoparticles loaded on pristine and boron oxide modified carbon nano-onions for enhanced ammonia electrooxidation in alkaline direct ammonia fuel cells

Cited by 18 publications

References 79 publications

Awakening (220) as One More Active Facet of PtMo Alloy via Single‐Atom Doping to Boost Ammonia Electrooxidation in Direct Ammonia Fuel Cell

Awakening (220) as One More Active Facet of PtMo Alloy via Single‐Atom Doping to Boost Ammonia Electrooxidation in Direct Ammonia Fuel Cell

Green Chemistry: Advanced Electrocatalysts and System Design for Ammonia Oxidation

Copper-Modified Carbon Nano-Onions as Electrode Modifiers for the Electroanalysis of the Antiretroviral Drug Efavirenz

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