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For the first time, a fast heating–cooling process is reported for the synthesis of carbon‐coated nickel (Ni) nanoparticles on a reduced graphene oxide (RGO) matrix (nano‐Ni@C/RGO) as a high‐performance H2O2fuel catalyst. The Joule heating temperature can reach up to ≈2400 K and the heating time can be less than 0.1 s. Ni microparticles with an average diameter of 2 µm can be directly converted into nanoparticles with an average diameter of 75 nm. The Ni nanoparticles embedded in RGO are evaluated for electro‐oxidation performance as a H2O2fuel in a direct peroxide–peroxide fuel cell, which exhibits an electro‐oxidation current density of 602 mA cm−2at 0.2 V (vs Ag/AgCl), ≈150 times higher than the original Ni microparticles embedded in the RGO matrix (micro‐Ni/RGO). The high‐temperature, fast Joule heating process also leads to a 4–5 nm conformal carbon coating on the surface of the Ni nanoparticles, which anchors them to the RGO nanosheets and leads to an excellent catalytic stability. The newly developed nano‐Ni@C/RGO composites by Joule heating hold great promise for a range of emerging energy applications, including the advanced anode materials of fuel cells.
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Highly Catalytic Amorphous Ni–P Synthesized via Pulsed Electrodeposition
Ni–P coatings have attracted wide attention due to their good tribological properties, corrosion resistance, and high catalytic activity. The surface properties impact the overall catalytic performance of Ni–P as electrocatalysts. In this study, highly catalytic amorphous Ni–P electrodeposits are synthesized using pulsed electrodeposition technique. Pulse parameters show a significant effect on the morphology, crystallinity, and electro‐catalytic activity of the deposits. The Ni–P deposits are found to be amorphous up to the duty cycle of 50%, whereas higher duty cycles (toward direct current deposition) result in a transition to nanocrystalline structure. This is attributed to an indirect reduction process involving intermediate phosphine leading to co‐deposition of phosphorus and nickel. Change in pulse frequency results in significant variations in surface morphology. Methanol electro‐oxidation in alkaline environment is studied as a function of surface morphology for the amorphous Ni–P catalysts. Up to four‐fold increase in oxidation peak current is observed for nano‐morphologies with large electrochemical surface area synthesized at pulse frequency of 50 Hz. This demonstrates the potential of pulsed electrodeposition as a versatile toolbox for obtaining highly catalytic amorphous Ni–P as a potential substitute for expensive noble‐metals used in direct alcohol fuel cells.
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- Award ID(s):
- 1561886
- PAR ID:
- 10088532
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Engineering Materials
- Volume:
- 21
- Issue:
- 7
- ISSN:
- 1438-1656
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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