Enhanced Redox Electrocatalysis in High-Entropy Perovskite Fluorides by Tailoring d-p Hybridization.

High-entropy catalysts featuring exceptional properties are, in no doubt, playing an increasingly significant role in aprotic lithium-oxygen batteries. Despite extensive effort devoted to tracing the origin of their unparalleled performance, the relationships between multiple active sites and reaction intermediates are still obscure. Here, enlightened by theoretical screening, we tailor a high-entropy perovskite fluoride (KCoMnNiMgZnF3-HEC) with various active sites to overcome the limitations of conventional catalysts in redox process. The entropy effect modulates the d-band center and d orbital occupancy of active centers, which optimizes the d-p hybridization between catalytic sites and key intermediates, enabling a moderate adsorption of LiO2 and thus reinforcing the reaction kinetics. As a result, the Li-O2 battery with KCoMnNiMgZnF3-HEC catalyst delivers a minimal discharge/charge polarization and long-term cycle stability, preceding majority of traditional catalysts reported. These encouraging results provide inspiring insights into the electron manipulation and d orbital structure optimization for advanced electrocatalyst.

π-Conjugation Induced Anchoring of Ferrocene on Graphdiyne Enable Shuttle-Free Redox Mediation in Lithium-Oxygen Batteries.

Soluble redox mediators (RMs), an alternative to conventional solid catalysts, have been considered an effective countermeasure to ameliorate sluggish kinetics in the cathode of a lithium-oxygen battery recently. Nevertheless, the high mobility of RMs leads to serious redox shuttling, which induces an undesired lithium-metal degeneration and RM decomposition during trade-off catalysis against the sustainable operation of batteries. Here, a novel carbon family of graphdiyne matrix is first proposed to decouple the charge-carrying redox property of ferrocene and the shuttle effects. It is demonstrated that a ferrocene-anchored graphdiyne framework can function as stationary RM, not only preserving the redox-mediating capability of ferrocene, but also promoting the local orientated three-dimensional (3D) growth of Li2 O2 . As a result, the RM-assisted catalysis in lithium-oxygen battery remains of remarkable efficiency and stability without the depletion of oxidized RMs or lithium degradation, resulting in a significantly enhanced electrochemical performance.

Synthesis of CdS-loaded (CuC10H26N6)3(PW12O40)2 for enhanced photocatalytic degradation of tetracycline under simulated solar light irradiation.

Largely discharged and excreted medical pollutants pose huge threats to ecosystems. However, typical photocatalysts, such as the Keggin-typed H3PW12O40, can hardly degrade these hazards under visible-light due to their broad bandgap and catalytic disability. In this work, the visible light harvesting was enabled by combining macrocyclic coordination compound CuC10H26N6Cl2O8 with H3PW12O40, and the resulting CuPW was loaded with CdS to reach robust catalytic ability to totally detoxify medicines. We prepared the CuPW-CdS composites through a facile precipitation method, and it showed excellent photocatalytic degradation for degrading tetracycline under visible-light irradiation. The (CuC10H26N6)3(PW12O40)2 with 10 wt% load of CdS shows the highest performance and is ∼6 times more efficient than the pure CuPW counterpart. The heterojunctional CuPW-CdS composites promote the separation of electrons and holes, and consequentially enhance photocatalytic activity. Thanks to migration of electrons from CdS to CuPW, the photocorrosion of CdS is prohibited, resulting in a high chemical stability during photocatalysis. In this work we design a new route to the multi-structural composite photocatalysts for practical applications in medical pollutant decontamination.