Prussian blue analogues are highly promising electrode materials due to their versatile electrochemical activity and low cost. However, they often suffer from severe structural damage caused by the Jahn–Teller distor...
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Prussian blue analogues are highly promising electrode materials due to their versatile electrochemical activity and low cost. However, they often suffer from severe structural damage caused by the Jahn–Teller distortion and dissolution of high-spin outer metal ions, resulting in poor cycle life. Material modification and electrolyte regulation have been the common approaches to address this issue, albeit with very limited success. We report here a novel and efficient strategy to preserve structural stability by co-inserting Co 2+ and Zn 2+ ions in KCo[Fe(CN) 6 ]. This co-insertion induced a spontaneous and reversible phase conversion by the replacement of low-spin inner ion (Fe 3+ ), which efficiently relieves structural damage caused by Jahn–Teller distortion and metal-ion dissolution, leading to an outstanding Zn 2+ storage capacity and an exceptional improvement of cycle life with a capacity retention of 97.7 % over 4400 cycles at 40 C. We also demonstrated the enhancement of co-intercalation on ion migration using a combined approach of experimental and density functional theory (DFT) calculations. This work provides an important progress to solve the cycle stability of Prussian blue analogues towards their practical application as electrode materials for aqueous batteries.
Realizing high energy-density and actual applications of fibre-based electrochemical supercapacitors (FESCs) are pivotal but challenging, as the ability to construct advanced fibres for accelerating charges kinetic di...
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Realizing high energy-density and actual applications of fibre-based electrochemical supercapacitors (FESCs) are pivotal but challenging, as the ability to construct advanced fibres for accelerating charges kinetic diffusion and Faradaic storage remain key bottlenecks. Here, we demonstrate high-performance FESCs based on hetero-structured polymetallic oxides/porous graphene core–sheath fibres, where the large pseudo-active polymetallic oxide (PMO) sheath is uniformly loaded on a hierarchical porous graphene fibre (PGF) core. Due to the abundant micro-/mesoporous pathways, large accessible surface, excellent redox activity and good interface electron conduction, the PMO-PGF possesses high areal capacitance (2959.78 mF cm −2 ) and manageable Faradaic reversibility in a 6 M KOH electrolyte. Furthermore, the PMO-PGF-based solid-state FESCs present high energy-density (187.22 μ Wh cm −2 ), long-life cycles (95.8 % capacitive retention after 20 000 cycles), diverse-powered capabilities and actual energy-supply applications.
Li-O 2 battery (LOB) is a promising “beyond Li-ion” technology with ultrahigh theoretical energy density (3457 Wh kg −1 ), while currently impeded by the sluggish cathodic kinetics of the reversible gas-solid reacti...
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Li-O 2 battery (LOB) is a promising “beyond Li-ion” technology with ultrahigh theoretical energy density (3457 Wh kg −1 ), while currently impeded by the sluggish cathodic kinetics of the reversible gas-solid reaction between O 2 and Li 2 O 2 . Despite many catalysts are developed for accelerating the conversion process, the lack of design guidance for achieving high performance makes catalysts exploring aleatory. The Sabatier principle is an acknowledged theory connecting the scaling relationship with heterogeneous catalytic activity, providing a tradeoff strategy for the topmost performance. Herein, a series of catalysts with wide-distributed d-band centers (i.e., wide range of adsorption strength) are elaborately constructed via high-entropy strategy, enabling an in-depth study of the Sabatier relations in electrocatalysts for LOBs. A volcano-type correlation of d-band center and catalytic activity emerges. Both theoretical and experimental results indicate that a moderate d-band center with appropriate adsorption strength propels the catalysts up to the top. As a demonstration of concept, the LOB using FeCoNiMnPtIr as catalyst provides an exceptional energy conversion efficiency of over 80 %, and works steadily for 2000 h with a high fixed specific capacity of 4000 mAh g −1 . This work certifies the applicability of Sabatier principle as a guidance for designing advanced heterogeneous catalysts assembled in LOBs.
Fine-tuning single-atom catalysts (SACs) to surpass their activity limit remains challenging at their atomic scale. Herein, we exploit p -type semiconducting character of SACs having a metal center coordinated to nitr...
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Fine-tuning single-atom catalysts (SACs) to surpass their activity limit remains challenging at their atomic scale. Herein, we exploit p -type semiconducting character of SACs having a metal center coordinated to nitrogen donors (MeN x ) and rectify their local charge density by an n -type semiconductor support. With iron phthalocyanine (FePc) as a model SAC, introducing an n -type gallium monosulfide that features a low work function generates a space-charged region across the junction interface, and causes distortion of the FeN 4 moiety and spin-state transition in the Fe II center. This catalyst shows an over two-fold higher specific oxygen-reduction activity than that of pristine FePc. We further employ three other n -type metal chalcogenides of varying work function as supports, and discover a linear correlation between the activities of the supported FeN 4 and the rectification degrees, which clearly indicates that SACs can be continuously tuned by this rectification strategy.
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