Li–CO2 batteries are regarded as a promising candidate for the next‐generation high‐performance electrochemical energy storage system owing to their ultrahigh theoretical energy density and environmentally friendly CO2 fixation ability. Until now, the majority of reported catalysts for Li–CO2 batteries are in the powder state. Thus, the air electrodes are produced in 2D rigid bulk structure and their electrochemical properties are negatively influenced by binder. The nondeformable feature and unsatisfactory performance of the cathode have already become the main obstacles that hinder Li–CO2 batteries toward ubiquity for wearable electronics. In this work, for the first time, a flexible hybrid fiber is reported comprising highly surface‐wrinkled and N‐doped carbon nanotube (CNT) networks anchored on metal wire as the cathode integrated with high performance and high flexibility for fiber‐shaped Li–CO2 battery. It exhibits a large discharge capacity as high as 9292.3 mAh g−1, an improved cycling performance of 45 cycles, and a decent rate capability. A quasi‐solid‐state flexible fiber‐shaped Li–CO2 battery is constructed to illustrate the advantages on mechanical flexibility of this fiber‐shaped cathode. Experiments and theoretical simulations prove that those doped pyridinic nitrogen atoms play a critical role in facilitating the kinetics of CO2 reduction and evolution reaction, thereby enabling distinctly enhanced electrochemical performance.
The current feasibility of nanocatalysts in clinical anti-infection therapy, especially for drug-resistant bacteria infection is extremely restrained because of the insufficient reactive oxygen generation. Herein, a novel Ag/Bi2MoO6 (Ag/BMO) nanozyme optimized by charge separation engineering with photoactivated sustainable peroxidase-mimicking activities and NIR-II photodynamic performance was synthesized by solvothermal reaction and photoreduction. The Ag/BMO nanozyme held satisfactory bactericidal performance against methicillin-resistant Staphylococcus aureus (MRSA) (~99.9%). The excellent antibacterial performance of Ag/BMO NPs was ascribed to the corporation of peroxidase-like activity, NIR-II photodynamic behavior, and acidity-enhanced release of Ag+. As revealed by theoretical calculations, the introduction of Ag to BMO made it easier to separate photo-triggered electron-hole pairs for ROS production. And the conduction and valence band potentials of Ag/BMO NPs were favorable for the reduction of O2 to ·O2−. Under 1064 nm laser irradiation, the electron transfer to BMO was beneficial to the reversible change of Mo5+/Mo6+, further improving the peroxidase-like catalytic activity and NIR-II photodynamic performance based on the Russell mechanism. In vivo, the Ag/BMO NPs exhibited promising therapeutic effects towards MRSA-infected wounds. This study enriches the nanozyme research and proves that nanozymes can be rationally optimized by charge separation engineering strategy.
Oxide
semiconductors like bismuth-based oxide or layered-double-hydroxide
accompanied by many surface oxygen vacancies (OVs) are emerging as
highly promising photocatalysts for artificial N2 fixation.
However, their band edge reduction potentials actually do not meet
nitrogen fixation requirements at all. The mechanism that triggers
the photocatalytic NH3 synthesis reaction still remains
unclear. Herein, taking BiOBr as a prototypical photocatalyst, we
reveal a photoexcitation-assisted N2 activation mechanism,
which can perfectly address the abovementioned problem. Specifically,
the OV defect states serve as a springboard that offers the photogenerated
electrons the reduction potential that is much higher than conduction
band edge under visible light. The physically adsorbed *N2 can trap the electron to form the *N2
•– transient state and collapse
into the *N2 vibrational excited state. This process deposits
a high amount of energy into *N2 and sharply lowers the
π* orbital of *N2 below the band edge, thereby allowing
*N2 to capture photogenerated electrons at band edge and
trigger the following NH3 synthesis. This study advances
the fundamental understanding of photocatalytic N2 fixation
and may provide an alternative way for the design of efficient ammonia
photocatalysts.
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