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The scientific community has been exploring advanced renewable energy solutions to address the serious challenges of energy depletion and environmental degradation brought about by the depletion of fossil fuels. To this end, fuel cells have attracted great interest due to their high efficiency and low pollution. Among them, direct ethanol fuel cells have great energy potential due to their low fuel toxicity, high efficiency of chemical-to-electric energy conversion, and easy access to biomass fuels.
However, the slow kinetics associated with EOR usually reduces the overall efficiency of defc, which poses a major obstacle to the large-scale application of these devices. Comprehensive studies have shown that pt-based composites are among the most effective catalysts for enhanced crude oil recovery (EOR). However, the practical application of these catalysts in defc faces a number of unresolved issues, such as the scarcity of Pt, poor resistance to poisoning, pure Pt-based catalysts, and low selectivity for c-single bond dc bond splitting.
The main point of this paper
Synthesis of PtCoCu ternary catalysts:
PtCoCu ternary catalysts were synthesized using a Joule-heated high-temperature thermal shock (TS) method with heating/cooling rates up to 103-105 K s-1, which is capable of ultra-rapid decomposition of the precursor to form metal nanoparticles in a few seconds
Characterization of TS-PtCoCu/CNTs composite electrocatalysts:
Achieved high Pt loading/utilization efficiency and effectively inhibited the growth or aggregation of PtCoCu nano-alloys.
Surfactant-free and reductant-free synthesis route for easy exposure of active sites.
High Pt conversion (feed to product) achieved through a more benign, simple and time-saving approach.
Importance of freeze-drying:
Freeze-drying prevents the agglomeration of carbon nanotubes and metal centers while ensuring the immobilization of the metal on the CNTs carrier.
Role of carbon nanotube scaffolds:
Carbon nanotube scaffolds act as reducing agents during in situ carbothermal reduction, facilitating the transformation of metal salts to alloys and eliminating the need for active site inhibiting surfactants and reducing agents.
Electron transfer and mass transfer facilitation:
The CNTs matrix promotes mass transfer and electron transfer in TS-PtCoCu/CNTs, improving the performance of the catalyst.
Performance advantages of PtCoCu alloy:
PtCoCu alloy not only has high activity, stability and durability, but also induces electron transfer under visible light to enhance the photo-assisted electrocatalytic performance.
Joule heating ultrafast thermal shock strategy:
In this study, a series of platinum-cobalt-copper ternary nano-alloys decorated with carbon nanotubes composites (TS-PtCoCu/CNTs) were prepared using an ultrafast thermal shock strategy of Joule heating without reductants or surfactants
Properties of TS-PtCoCu/CNTs:
TS-PtCoCu/CNTs with optimal Pt content (∼15%) exhibited excellent EOR activity with mass and specific activities of 3.58 A mgPt-1 and 5.79 mA cm-2, respectively, which were 3.8 and 13.5 times higher than those of Pt/C
Comparison with conventional methods:
The catalyst also showed excellent activity and stability compared to the control prepared by the conventional furnace annealing method
Understanding of catalyst performance by DFT calculations:
DFT calculations revealed that TS-PtCoCu/CNTs have downshifted d-band centers, attenuated CO adsorption, and higher OH affinity compared to monometallic Pt, all of which lead to the preferred C1 pathway for EOR
Catalyst construction method:
In this study, we demonstrate an ultrafast construction method for an efficient Pt-Cu-Cu ternary catalyst for EOR, with an in-depth discussion of the reaction mechanism, including structural characterization, electrochemical characterization, and theoretical calculations
Advantages of the Joule heating method:
The Joule heating method is characterized by rapid, energy-saving and self-heating, and the in situ synthesis of catalysts is achieved by rapid warming and cooling, which is suitable for large-scale and low-cost production
Stability of the catalyst:
The prepared catalyst showed minimal change in overpotential after continuous operation at high current density, indicating that the catalyst has excellent activity and stability
Active site availability:
The catalyst prepared by the Joule heating method provided a large number of active sites with moderate hydrogen adsorption free energy, which facilitated the electrocatalytic reaction
Strong chemical bonding:
The strong chemical bonding between the catalyst and the carbon nanotubes significantly enhances the mechanical stability and avoids the problem of catalyst detachment from the electrode at high current densities
In conclusion, this study presents a novel heat-shock method to fabricate EOR catalysts based on platinum-cobalt-copper alloys without the use of harsh reducing agents or surfactants. Thanks to the ultra-fast heating/cooling rate, the preparation process of ternary alloy-decorated carbon nanotube composites takes only a few seconds. Through careful optimization of the platinum content, TS-PtCoCu/CNTs outperform Pt/C benchmark catalysts and similar catalysts obtained through conventional furnace annealing processes in terms of activity, reaction kinetics and durability. The catalysts also outperformed many other previously reported catalysts based on Pt alloys.DFT calculations showed that the incorporation of smaller-sized Co/Cu atoms into Pt monoclonal cells shifted the d-band center of Pt downward, weakened the adsorption of CO, and increased the binding of OH, which ultimately resulted in the preference of the C1 pathway during ethanol oxidation. Therefore, this study reports an ultra-fast, scalable and cost-effective approach to the development of Pt-based ternary alloy catalysts, which will provide valuable insights into the design of highly efficient catalysts suitable for a wider range of fuel cells.
