Precise regulation of the electronic states of catalytic sites through molecular engineering is highly desired to boost catalytic performance. Herein, a facile strategy was developed to synthesize efficient oxygen reduction reaction (ORR) catalysts, based on mononuclear iron phthalocyanine supported on commercially available multi‐walled carbon nanotubes that contain electron‐donating functional groups (FePc/CNT‐R, with “R” being −NH2, −OH, or −COOH). These functional groups acted as axial ligands that coordinated to the Fe site, confirmed by X‐ray photoelectron spectroscopy and synchrotron‐radiation‐based X‐ray absorption fine structure. Experimental results showed that FePc/CNT‐NH2, with the most electron‐donating −NH2 axial ligand, exhibited the highest ORR activity with a positive onset potential (Eonset=1.0 V vs. reversible hydrogen electrode) and half‐wave potential (E1/2=0.92 V). This was better than the state‐of‐the‐art Pt/C catalyst (Eonset=1.00 V and E1/2=0.85 V) under the same conditions. Overall, the functionalized FePc/CNT‐R assemblies showed enhanced ORR performance in comparison to the non‐functionalized FePc/CNT assembly. The origin of this behavior was investigated using density functional theory calculations, which demonstrated that the coordination of electron‐donating groups to FePc facilitated the adsorption and activation of oxygen. This study not only demonstrates a series of advanced ORR electrocatalysts, but also introduces a feasible strategy for the rational design of highly active electrocatalysts for other proton‐coupled electron transfer reactions.
Cells with 5 wt%, 10 wt%, and 15 wt% PP1, CNFSI addition exhibit higher initial discharge capacities than the cell with blank electrolyte. The addition of IL with suitable amount significantly increases the cycle performance..
Electrochemical oxygen reduction is essential for a variety of sustainable energy application technologies. The development of non-noble metal based electrocatalysts with durable stability and lower overpotentials is still a challenge. According to the reaction mechanism, the difficulty is originated from large equilibrium potential for *OO À formation and high instability of it. Here, we synthesized a 2D electrocatalytic material with nano-Co 3 O 4 supported on ionic liquid-functionalized graphene oxide (Co 3 O 4 /ILÀ GO). Experimental results show the heterogenization strategy of IL enables anodic shifts of approximately 150 and 145 mV for the initial and half-wave potentials, respectively, enabling Co 3 O 4 /ILÀ GO a comparable activity to the state-of-the-art Pt/C catalyst. Moreover, Co 3 O 4 /ILÀ GO exhibits an excellent tolerance to methanol and superior long-term stability over Pt/ C making it a promising candidate for ORR in alkaline solutions. Theoretical calculations show the functionalized IL stabilizes the high-energy CoÀ OO À intermediate through a strong pairing effect between the IL cation and the unstable *OO À adduct, and lowers the energy barrier for the subsequent CoÀ OOH formation, which enables the hybrid material a comparable activity and superior durability to Pt/C. To the best of our knowledge, this is the first exploration for heterogenization of IL onto electrode to stabilize crucial intermediates and subsequently boost the catalytic performance.
Wireless power transfer (WPT) techniques have gained wide acceptance across a range of battery charging applications such as cell phones, cardiac pacemakers, and electric vehicles. In a wireless battery charging system, a constant current/constant voltage (CC/CV) charging strategy, regardless of the variation of the battery load which may roughly range from a few ohms to several hundred ohms, is typically adopted to ensure the safety, durability, and performance of the battery. However, system efficiency drops significantly as the load increases in CV mode, especially at very light-load conditions. This paper proposes an efficiency optimization method for an LCC-parallel compensated inductive power transfer (IPT) battery charging system without the help of any additional power converter and control method. The equivalent circuit and resonant conditions of the LCC-parallel compensation topology are firstly analyzed to achieve the load-independent CV output at a zero phase angle (ZPA) operating frequency. Over the full range of CV charging mode, the efficiency of the LCC-parallel resonant tank circuit is analyzed and optimized. An IPT battery charger prototype with 48 V charging voltage and 1 A charging current is implemented. A measured DC–DC transfer efficiency of greater than 90.48% is achieved during the whole CV charging profile.
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