Designing electrochemical interfaces for in vivo analysis of neurochemicals with high selectivity and long-term stability is vital for monitoring dynamic variation and dissecting the complex mechanisms of pathogenesis in living animals. This review focuses on the development of electrochemical interfaces based on rational design of molecular probes for in vivo measurement with high selectivity and high stability from three aspects: (1) Specific recognition probes were rationally designed and created to remarkably improve the selectivity of in vivo analysis in a complicated brain environment. (2) The Au-C≡C functionalized surface was developed to remarkably enhance the stability of molecular assembly, and employed for real-time mapping and accurate quantification in the brains. (3) Combined with the Au-C≡C functionalized molecular probe, the new type anti-biofouling microfiber array was established to achieve long-term and real-time monitoring dynamic changes in the brain. At last, some perspectives are highlighted in the further development of the efficient electrochemical interfaces for in vivo detection in the brain.
The rapid development of electric vehicles urgently requires high-energy-density batteries. Recently, metal-air batteries have attracted much attention in industry and academia for their ultra-high theoretical energy densities. However, the practical application of metal-air batteries is severely impeded by multiple drawbacks, including severe side reactions, low energy efficiency, and limited cycle life. Understanding the reaction mechanism of the cell and further developing effective strategies are beneficial for the practical application of metal-air batteries. In the past decade, advanced characterization techniques have accelerated the development of metal-air batteries. In particular, synchrotron radiation-based characterization techniques have been widely applied to the mechanistic study of metal-air batteries due to their non-destructive detection capability and high resolution. In this review, various synchrotron radiation-based characterization techniques are systematically summarized to understand the local structure and chemistry of metal-air batteries, with a special focus on how these advanced techniques can help understand the essence of degradation mechanism and optimization strategies. This progress report aims to highlight the crucial role of synchrotron radiation characterization for mechanism understanding of metal-air batteries.
Electrochemical/electrocatalytic technology has played a central role in achieving highly efficient energy conversion and storage. To date, the in-depth electrochemical research begins to require accurate and multi-dimensional information of electrochemical interfaces, which usually relies on the application of in situ characterizations. Electrical transport spectroscopy (ETS) is a newly developed measurement strategy based on chip-platform, and provides in situ information of electrochemical interfaces from a novel perspective due to a signal origin that is fundamentally different from typical spectroscopic and electrochemical techniques. In this tutorial review, the working principle and experimental setup of ETS are described in detail with the demonstration of several model electrocatalytic materials, including metal nanoparticle/nanowires, two-dimensional layered materials, nickel based hydroxide/oxyhydroxides and dissimilatory metal-reducing bacteria. The advantages of ETS are summarized, and the future challenges and opportunities that ETS faces are also prospected.
Light irradiation on silver nanoparticles (Ag NPs) could cause the energy conversion, thus, the fragmentation of Ag NPs. It is important to detect the changes of fragmented Ag NPs in the aspects of physical and chemical properties. Herein, benefiting from the high sensitivity, high temporal resolution, and high-throughput, single entity electrochemistry (SEE) method is introduced to in-situ track the dynamic laser fragmentation of single Ag NP. Compared with UV-Vis absorption spectroscopy and transmission electron microscopy (TEM), SEE methods enables an accurate in-situ measurements of light-induced fragmentation of single Ag NP. The variation in the statistic current amplitude displays the real-time changes of single Ag NP upon laser irradiation for 60 min, which indicates that the laser of 532 nm wavelength is the most effective laser for the dynamic fragmentation. By virtue of the excellent sensing performance, SEE is further applied in revealing the heterogeneity in Ag NPs’ intrinsic physicochemical properties, such as size, crystal structure, surface charge density. The study highlights the potential of SEE to advancing the real-time characterization of nanomaterials in the chemical reactions.
As an electrochemical energy conversion system, fuel cell has the advantages of high energy conversion efficiency and high cleanliness. Oxygen reduction reaction (ORR), as an important cathode reaction in fuel cells, has received extensive attention. At present, the electrocatalysts are still one of the key materials restricting the further commercialization of fuel cells. The fundamental understanding on the catalytic mechanism of ORR is conducive to the development of electrocatalysts with the enhanced activity and high selectivity. This review aims to summarize the in situ characterization techniques used to study ORR. From this perspective, we first briefly introduce the advantages of various in situ techniques in ORR research, including electrochemical scanning tunneling microscopy, infrared spectroscopy, Raman spectroscopy, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Then, the applications of various in situ characterization techniques in characterizing of the catalyst morphological evolution and electronic structure as well as the identification of reactants and intermediates in the catalytic process are summarized. Finally, the future development of in situ technology is outlooked.
The development of highly efficient and cost-effective electrocatalysts for the sluggish oxygen evolution reaction (OER) remains a significant barrier to establish effective utilization of renewable energy storage systems and water splitting to produce clean fuel. The current status of the research in developing OER catalysts shows that NiFe-based oxygen evolution catalysts (OECs) have been proven as excellent and remarkable candidates for this purpose. But it is critically important to understand the factors that influence their activity and underlying mechanism for the development of state-of-the-art OER catalysts. Therefore, the development of in-situ/operando characterizations is urgently required to detect key intermediates along with active sites and phases responsible for OER. 57Fe Mössbauer spectroscopy is one of the appropriate and suitable techniques for determining the phase structure of catalysts under their electrochemical working conditions, identifying the active sites, clarifying the catalytic mechanisms, and determining the relationship between catalytic activity and the coordination structure of catalysts. In this tutorial review, we have discussed the current status of research on NiFe-based catalysts with particular attention to introduce in detail the knowhow about the development and utilization of in-situ/operando57Fe Mössbauer-electrochemical spectroscopy for the study of OER mechanism. A brief overview using NiFe-(oxy)hydroxide catalysts, derived from ordered porous metal-organic framework (MOF) material NiFe-PBAs (Prussian blue analogues), as a typical model study case for the OER electrocatalyst and self-designed in-situ/operando57Fe Mössbauer-electrochemical instrument, has been provided for the better understanding of readers. Moreover, using in-situ/operando57Fe Mössbauer spectroscopy, the crucial role of Fe species during OER reaction has been explained very well.
Brain, as the source of neural activities such as perceptions and emotions, consists of the dynamic and complex networks of neurons that implement brain functions through electrical and chemical interactions. Therefore, analyzing and monitoring neurochemicals in living brain can greatly contribute to uncovering the molecular mechanism in both physiological and pathological processes, and to taking a further step in developing precise medical diagnosis and treatment against brain diseases. Through collaborations across disciplines, a handful of analytical tools have been proven to be befitting in neurochemical measurement, spanning the level of vesicles, cells, and living brains. Among these, electrochemical methods endowed with high sensitivity and spatiotemporal resolution provide a promising way to precisely describe the dynamics of target neurochemicals during various neural activities. In this review, we expand the discussion on strategies to address two key issues of in vivo electrochemical sensing, namely, selectivity and biocompatibility, taking our latest studies as typical examples. We systematically elaborate for the first time the rationale behind engineering electrode/brain interface, as well as the unique advantages of potentiometric sensing methods. In particular, we highlight our recent progress on employing the as-prepared in vivo electrochemical sensors to unravel the molecular mechanism of ascorbate in physiological and pathological processes, aiming to draw a blueprint for the future development of in vivo electrochemical sensing of brain neurochemicals.
Non-nucleophilic electrolytes are promising next-generation highly stable electrolytes for magnesium-ion batteries (MIBs). However, a passivation layer on Mg metal anode usually blocks Mg2+ diffusion, leading to poor reaction kinetics and low Coulombic efficiency of the Mg plating/stripping in these electrolytes. Here we explore the utilization of phenyl disulfide (PDF) as a film-forming additive for non-nucleophilic electrolytes to regulate the interfacial chemistry on Mg metal anode. Phenyl-thiolate generated from the PDF additive was found to suppress the unfavorable surface blocking layer, resulted in a high Coulombic efficiency of up to 99.5% for the Mg plating/stripping process as well as a remarkably decreased overpotential. The full battery consisting of Mg metal anode and Mo6S7Se cathode remained stable in the PDF additive-containing electrolyte at 0.1 C over 150 cycles at room temperature.