Transition metals and related compounds are known to exhibit high catalytic activities in various electrochemical reactions thanks to their intriguing electronic structures. What is lesser known is their unique role in storing and transferring electrons in battery electrodes which undergo additional solid-state conversion reactions and exhibit substantially large extra capacities. Here, a full dynamic picture depicting the generation and evolution of electrochemical interfaces in the presence of metallic nanoparticles is revealed in a model CoCO3/Li battery via an in situ magnetometry technique. Beyond the conventional reduction to a Li2CO3/Co mixture under battery operation, further decomposition of Li2CO3 is realized by releasing interfacially stored electrons from its adjacent Co nanoparticles, whose subtle variation in the electronic structure during this charge transfer process has been monitored in real time. The findings in this work may not only inspire future development of advanced electrode materials for next-generation energy storage devices but also open up opportunities in achieving in situ monitoring of important electrocatalytic processes in many energy conversion and storage systems.
Zhang Ting,Liu Gang-Qin,Leong Weng-Hang,Liu Chu-Feng,Kwok Man-Hin,Ngai To,Liu Ren-Bao,Li Quan
Diamond nitrogen-vacancy (NV) center-based magnetometry provides a unique opportunity for quantum bio-sensing. However, NV centers are not sensitive to parameters such as temperature and pressure, and immune to many biochemical parameters such as pH and non-magnetic biomolecules. Here, we propose a scheme that can potentially enable the measurement of various biochemical parameters using diamond quantum sensing, by employing stimulus-responsive hydrogels as a spacing transducer in-between a nanodiamond (ND, with NV centers) and magnetic nanoparticles (MNPs). The volume phase transition of hydrogel upon stimulation leads to sharp variation in the separation distance between the MNPs and the ND. This in turn changes the magnetic field that the NV centers can detect sensitively. We construct a temperature sensor under this hybrid scheme and show the proof-of-the-principle demonstration of reversible temperature sensing. Applications in the detection of other bio-relevant parameters are envisioned if appropriate types of hydrogels can be engineered.
危险品化学品经营许可证（带存储）