Electrolyte-Philic Electrode Material with a Functional Polymer Brush

Ratiometric Electrochemical Sensor Applying SWCNHs/T-PEDOT Nanocomposites for Efficient Quantification of Tert-Butylhydroquinone in Foodstuffs

Tert-butylhydroquinone (TBHQ) is a phenolic substance that is commonly employed to prevent food oxidation. Excessive or improper utilization of this antioxidant can not only impact food quality but may also pose potential risks to human health. In this study, an ultrasensitive, stable, and easily operable ratiometric electrochemical sensor was successfully fabricated by combining the tubular (3,4-ethylenedioxythiophene) (T-PEDOT) with single-wall carbon nanohorns (SWCNHs) for the detection of TBHQ antioxidants in food. The SWCNHs/T-PEDOT nanocomposite fabricated through ultrasound-assisted and template approaches was employed as the modified substrate for the electrode interface. The synergistic effect of SWCNHs and T-PEDOT, which possess excellent electrical conductivity and catalytic properties, enabled the modified electrode to showcase remarkable electrocatalytic performance towards TBHQ, with the redox signal of methylene blue serving as an internal reference. Under optimized conditions, the SWCNHs/T-PEDOT-modified electrode demonstrated good linearity within the TBHQ concentration range of 0.01-200.0 μg mL-1, featuring a low limit of detection (LOD) of 0.005 μg mL-1. The proposed ratiometric electrochemical sensor displayed favorable reproducibility, stability, and anti-interference capacity, thereby offering a promising strategy for monitoring the levels of TBHQ in oil-rich food products.

Enabling High-Capacitance Supercapacitors by Polyelectrolyte Brushes

Polyelectrolyte brushes (PEBs) hold excellent potential for designing high-capacitance electrical double-layer capacitors (EDLCs), a crucial component of supercapacitors. Both experiments and computational simulations have shown their energy-storage advantage. However, the effect of PEBs on the energy storage of EDLCs is not yet fully understood. Herein, we systematically study the energy-storage effects of polyanionic (PA) and polycationic (PC) brushes using polymer density functional theory (DFT). First, the application of polymer DFT in polyelectrolyte-grafted EDLCs is successfully validated using molecular dynamics simulations. With the help of polymer DFT, an interfacial adhesion microstructure of the PA/PC brushes is observed. Most importantly, the results show that polyelectrolyte-grafted EDLCs achieve a significant increase in capacitance at low salt concentrations and surface voltages, offering an excellent energy-storage advantage over traditional EDLCs. However, this advantage is considerably diminished at high salt concentrations or surface voltages, showing unusual salt- and voltage-dependent behaviors of energy-storage capacity. Nonetheless, the PC-grafted EDLCs maintain their outstanding energy-storage performance, even at relatively high salt concentrations and surface voltages. These findings deepen our comprehension of PEBs at the molecular level and provide insights for the molecular design of high-capacitance supercapacitors.

Electrolyte-Wettability Issues and Challenges of Electrode Materials in Electrochemical Energy Storage, Energy Conversion, and Beyond

The electrolyte-wettability of electrode materials in liquid electrolytes plays a crucial role in electrochemical energy storage, conversion systems, and beyond relied on interface electrochemical process. However, most electrode materials do not have satisfactory electrolyte-wettability for possibly electrochemical reaction. In the last 30 years, there are a lot of literature have directed at exploiting methods to improve electrolyte-wettability of electrodes, understanding basic electrolyte-wettability mechanisms of electrode materials, exploring the effect of electrolyte-wettability on its electrochemical energy storage, conversion, and beyond performance. This review systematically and comprehensively evaluates the effect of electrolyte-wettability on electrochemical energy storage performance of the electrode materials used in supercapacitors, metal ion batteries, and metal-based batteries, electrochemical energy conversion performance of the electrode materials used in fuel cells and electrochemical water splitting systems, as well as capacitive deionization performance of the electrode materials used in capacitive deionization systems. Finally, the challenges in approaches for improving electrolyte-wettability of electrode materials, characterization techniques of electrolyte-wettability, as well as electrolyte-wettability of electrode materials applied in special environment and other electrochemical systems with electrodes and liquid electrolytes, which gives future possible directions for constructing interesting electrolyte-wettability to meet the demand of high electrochemical performance, are also discussed.

Modified KBBF-like Material for Energy Storage Applications: ZnNiBO3(OH) with Enhanced Cycle Life

Not only are new and novel materials sought for electrode material development, but safe and nontoxic materials are also highly being intensively investigated. Herein, we prepare ZnNiBO₃(OH) (ZNBH), a modified and Be-free KBe₂BO₃F₂ (KBBF) family member as an effective electrode material. The novel ZNBH resembles the KBBF structure but with reinforced structure and bonding, in addition to well-incorporated conductive metals benefiting supercapacitor applications. The enhanced electronic properties of ZNBH are further studied by means of density functional theory calculations. The as-prepared ZNBH electrode material exhibits a specific capacity of 746 C g^-1 at a current density of 1 A g^-1. A hybrid supercapacitor (HSC) device is fabricated and successfully illuminated multiple color LEDs. Interestingly, even after being subjected to long charge-discharge for 10 000 cycles, the ZNBH//AC HSC device retains 97.2% of its maximum capacity, indicating the practicality of ZNBH as an electrode material.

Effect of Conductivity on In Situ Deactivation of Catechol-Boronate Complexation-Based Reversible Smart Adhesive

To reduce the need for elevated electrical potential to deactivate catechol-based smart adhesive and preserve its reversibility, conductive 1-pyrenemethyl methacrylate (PyMA) was incorporated into a catechol and phenylboronic acid-containing adhesive coating immobilized on aluminum (Al) discs. Electrochemical impedance spectroscopy (EIS) indicated that incorporation of 26 mol % of PyMA reduced ionic resistance (R_s) and charge-transfer resistance (R_c) of the coating from over 22 Ω/mm² to 5.9 and 1.2 Ω/mm², respectively. A custom-built Johnson-Kendall-Roberts (JKR) contact mechanics test setup was used to evaluate the adhesive property of the coating with in situ applied electricity using a titanium (Ti) sphere both as a test substrate as well as the cathode for application of electricity and the Al disc as the anode. The adhesive coating demonstrated over 95% reduction in the adhesive property when electricity (1-2 V) was applied while the adhesive was in direct contact with the Ti surface. The addition of PyMA enables the deactivation of the adhesive using a voltage as low as 1 V. Both cyclic voltammetry (CV) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra confirmed the formation of catechol-boronate complexation through electrochemical stimulation. Breaking the complex with an acidic buffer (pH 3) recovered the catechol for strong wet adhesion and the coating could be repeatedly deactivated and reactivated using low electrical potential for up to five cycles. Incorporation of both conductive PyMA and boronic acid as the temporary protecting group was required to achieve rapidly switchable adhesive that could be deactivated with low applied voltage.

Dual High-Conductivity Networks via Importing a Polymeric Gel Electrolyte into the Electrode Bulk

To obtain high-ionic-conductivity and high-electron-conductivity electrode materials, we design novel dual high-conductivity networks through importing a polymeric gel electrolyte into the electrode bulk by doping gold nanoparticles, which endows the membrane electrode with not only a high electron conductivity of 1.66 s·cm^-1 but also a high ionic conductivity of 2.7 × 10^-2 s·cm^-1, as well as a good surface area capacitance of 1098 mF·cm^-2 at 0.5 mA·cm^-2. The membrane electrode shows great mechanical strength, high flexibility, and tremendous stability, and the design concept based on dual conductive networks could be also applied to other electrode systems and other energy storage fields.