Understanding the role of oxidation state of Cu surface and surface-adsorbed intermediate species in electrochemical CO2 reduction is crucial for the development of selective CO2-to-fuel electrocatalysts. In this study, the electrochemical CO2 reduction mechanism over the Cu catalysts with various oxidation states was studied by using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS), in situ soft X-ray absorption spectroscopy (Cu L-edge) and on-line gas chromatography measurements. The atop-adsorbed CO (COatop) intermediate is obtained on the electrodeposited Cu surface which primarily has the oxidation state of Cu(I). COatop is further reduced, followed by the formation of C1 product such as CH4. The residual bridge-adsorbed CO (CObridge) is formed on the as-prepared Cu surface with Cu(0) which inhibits hydrocarbon formation. In contrast, the CV-treated Cu electrode prepared by oxidizing the as-prepared Cu surface contains different amount of Cu(I) and Cu(0) states. The major theme of this work is that in situ SEIRAS results show the coexistence of COatop and CObridge as the reaction intermediates during CO2 reduction and the selectivity of CO2-to-ethylene conversion is further enhanced in the CV-treated Cu electrode. The Cu catalysts modulated by electrochemical method exhibit different oxidation states and reaction intermediates as well as the electrocatalytic properties.

This study reports a highly sensitive mercury ion sensor composed of the zincophosphite framework nanoparticle (NTOU4nano) blended with in situ synthesized conductive polyaniline (PANI). High stability of the pristine zincophosphite solid not only renders a facile nanosizing treatment feasible but also allows it to withstand the electrochemical PANI deposition at a low pH condition. PANI significantly enhances the surface coverage concentration and increases the electron transfer capability of the resulting composite. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), hydrodynamic amperometry, and electrochemical impedance spectroscopy (EIS) are used to characterize and optimize the electroanalytical performance of the nanocomposite. The resulting electrochemical sensor shows a linear dynamic range for mercury ion detection ranging from 0.05 to 27.5 nM and exhibits one of the lowest limits of detection (LODs) of 3.49 × 10–11 M reported using crystalline organic–inorganic hybrids. Additionally, the practical utility of the nanocomposite for mercury ion sensing is demonstrated using water samples containing high salt concentrations, as well as from the environment including the seawater and river water. In short, the reported nanocomposite is among one of the first metallophosphite materials being consolidated with PANI as an integrated sensing platform for highly sensitive mercury ion detection and holds good promise for early-warning application.

Lithium metal anode material suffers from the formation of a dendritic structure and manufacturing difficulties in Li metal batteries. Although anode-free lithium metal batteries (AFLMBs) have received broad interest due to their high energy density and easy fabrication, controlling the morphology of electrodeposited Li is challenging. In this work, we report on the use of mesoporous silica thin films (MSTFs) with perpendicular nanochannel (pore size ∼6 nm) stacking on a stainless steel (SS) substrate as the MSTF⊥SS for advancing AFLMBs. The MSTF⊥SS substrate with inorganic structures improves the stability of the Li plating/stripping process in Li-MSTF⊥SS cells at a current density of 2 mA cm −2 and capacity of 2 mAh cm −2 . A LiFePO 4 cathode (mass loading: ∼12 mg cm −2 ) paired with the MSTF⊥SS electrode delivered an initial discharge capacity of 154 mA h g −1 , which is ∼20% higher than that of the bare SS electrode at a C rate of 0.1C. Grazing-incidence wide-angle X-ray scattering results suggest that MSTF regulates the Li electrodeposition process with individual microcrystals and leads to the formation of Li(110). Also, the electrodeposited Li film with a uniform surface is obtained on the MSTF⊥SS substrate. The designed porous MSTF with high stability, ultrasmall pore size, and lithiophilic properties enhances the performance of AFLMBs with the LiFePO 4 cathode during 100 cycles.

Developing functional materials that directly integrate into miniaturized devices for sensing applications is essential for constructing the next-generation point-of-care system. Although crystalline structure materials such as metal organic frameworks are attractive materials exhibiting promising potential for biosensing, their integration into miniaturized devices is limited. Dopamine (DA) is a major neurotransmitter released by dopaminergic neurons and has huge implications in neurodegenerative diseases. Integrated microfluidic biosensors capable of sensitive monitoring of DA from mass-limited samples is thus of significant importance. In this study, we developed and systematically characterized a microfluidic biosensor functionalized with the hybrid material composed of indium phosphate and polyaniline nanointerfaces for DA detection. Under the flowing operation, this biosensor displays a linear dynamic sensing range going from 10 −18 to 10 −11 M and a limit of detection (LOD) value of 1.83 × 10 −19 M. In addition to the high sensitivity, this microfluidic sensor showed good selectivity toward DA and high stability (>1000 cycles). Further, the reliability and practical utility of the microfluidic biosensor were demonstrated using the neuro-2A cells treated with the activator, promoter, and inhibiter. These promising results underscore the importance and potential of microfluidic biosensors integrated with hybrid materials as advanced biosensors systems.