Guofeng Cui

The design of carbonate-selective electrodes with high sensitivity, stability, and selectivity holds significant potential for applications in marine environmental monitoring. In this study, a novel pine-leaf porous structure carbonate ion-selective electrode was prepared with a solid contact layer of silver nanoparticles/polyaniline (AgNPs@PANI) using a two-step electrochemical method involving electropolymerized PANI and electrodeposited AgNPs. The novel structure provides additional charge transport paths and a larger contact area for carbonate ions passing through the selective membrane, thereby enhancing the membrane's carbonate-responsive performance. The results indicate that the GE/AgNPs@PANI/CO₃ ²⁻-ISE demonstrates a near-Nernst response (−29.5 ± 0.2 mV per decade) to carbonate ions over a wide concentration range (10⁻¹–10⁻⁶ M) as well as a low carbonate detection limit (1.15 × 10⁻⁷ M), with excellent performance in terms of response speed (5.5 s), reversibility (1.35 mV), long-term potential stability (0.17 mV h⁻¹), and selectivity. The developed electrode was applied to the detection of carbonate in real seawater using the standard addition method, and the average recovery was found to be 95–105%. Meanwhile, the results of carbonate ion detection in real samples using this electrode were largely consistent with those obtained by potentiometric titration, demonstrating significant practicality in marine chemistry research.

The exploitation of ion-selective membranes with high power density and low resistance is crucial for harvesting osmotic energy in natural environments. However, the exploration of membranes that synergistically satisfy the demands of these properties in osmotic energy conversion remains largely unresolved. Herein, we demonstrate the application of a negative surface-modified 3D porous poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) hydrogel for osmotic membranes, which effectively improved their deficiencies. Experiments, validation and simulations confirmed that the hydrogel membranes have remarkable space charge-modulated ion transport properties. Consequently, an impressive power output of 6.26 W m⁻² can be realized, which exceeds the prevailing commercial standard (5 W m⁻²). Meanwhile, five device units were connected in series to charge a supercapacitor which exhibited an impressive selectivity rate of 95.6%, coupled with an electrochemical energy conversion efficiency of approximately 45.8%. This research paves a new avenue towards the application of hydrogels in ultra-high performance osmotic membranes.

Ion transportation via the mixed mechanisms of hydrogels underpins ultrafast biological signal transmission in nature, and its application to the rapid and sensitive sensing detection of human specific ions is of great interest for the field of medical science. However, current research efforts are still unable to achieve transmission results that are comparable to those of bioelectric signals. Herein, 3D interconnected nanochannels based on poly(pyrrole-co-dopamine)/poly(vinyl alcohol) (P(Py-co-DA)/PVA) supernetwork conductive hydrogels are designed and fabricated as stimuli-responsive structures for K⁺ ions. Distinct from conventional configurations, which exhibit rapid electron transfer and permeability to biosubstrates, interconnected nanofluidic nanochannels collaborated with the P(Py-co-DA) conductive polymer in the supernetwork conductive hydrogel significantly improve conductivity (88.3 mS/cm), ion transport time (0.1 s), and ion sensitivity (74.6 mV/dec). The faster ion response time is attributed to the synergism of excellent conductivity originating from the P(Py-co-DA) polymer and the electronic effect in the interconnected nanofluidic channels. Furthermore, the supernetwork conductive hydrogel demonstrates K⁺ ion selectivity relative to other cations in biofluids such as Na⁺, Mg²⁺, and Ca²⁺. The DFT calculation indicates that the small solvation energy and low chemical transfer resistance are the main reasons for the excellent K⁺ ion selectivity. Finite element analysis (FEA) simulations further support these experimental results. Consequently, the P(Py-co-DA)/PVA supernetwork conductive hydrogels enriched with the 3D interconnected nanofluidic channels developed in this work possess excellent sensing of K⁺ ions. This strategy provides great insight into efficient ion sensing in traditional biomedical sensing that has not been explored by previous researchers.

An electrochemical strategy for the simultaneous detection of DA and EP with high sensitivity by cyclic square wave voltammetry using a modified open source potentiostat.

Zn batteries are considered the new-generation candidate for large-scale energy storage systems, taking both safety and environmental problems into account. They are still restricted by unexpected dendrite/byproducts occurring on the Zn anodes. We hereby screen a powerful polymer type additive, hyaluronic acid (HA), to regulate the typical ZnSO₄ electrolyte for obtaining dendrite-free Zn ion batteries. The intrinsically chaotropic property of the HA molecule can efficiently destruct the original hydrogen-bonds from H₂O-H₂O, thus restricting the common parasitic reactions derived from the large amount of active water molecules. Simultaneously, the abundant functional groups along the long chain from HA additives can construct an effective tunnel for transferring Zn²⁺ smoothly, enabling an obviously improved Zn ion transference number of 0.62. Owning to the above intriguing mechanism for regulating the solvation structure of electrolyte systems, the HA additives can greatly increase the cycling life of Zn-Zn symmetric cells to 2200 and 800 h under the conditions of 1 mA cm^-2/1 mAh cm^-2 and 5 mA cm^-2/5 mAh cm^-2, respectively. Modified performance for both Zn-Ti and Zn-MnO₂ can all be realized by this valid additive, elucidating it can be potentially utilized in large-scale Zn based aqueous energy storage devices.

A graphene-based electrochemical flow analysis device for simultaneous determination of dopamine, 5-hydroxytryptamine, and melatonin.

The stability of Zn anode in various Zn-based energy storage devices is the key problem to be solved. Herein, aromatic aldehyde additives are selected to modulate the interface reactions between the Zn anode and electrolyte. Through comprehensively considering electrochemical measurements, DFT calculations and FEA simulations, novel mechanisms of one kind of aromatic aldehyde, veratraldehyde in inhibiting Zn dendrite/by-products can be obtained. This additive prefers to absorb on the Zn surface than H₂O molecules and Zn²⁺, while competes with hydrogen evolution reaction and Zn plating/stripping process via redox reactions, thus preventing the decomposition of active H₂O near the interface and uncontrollable Zn dendrite growth via a synactic absorption-competition mechanism. As a result, Zn–Zn symmetric cells with the veratraldehyde additive realize an excellent cycling life of 3200 h under 1 mA cm⁻²/1 mAh cm⁻² and over 800 h even under 5 mA cm⁻²/5 mAh cm⁻². Moreover, Zn–Ti and Zn–MnO₂ cells with the veratraldehyde additive both obtain elevated performance than that with pure ZnSO₄ electrolyte. Finally, two more aromatic aldehyde additives are chosen to prove their universality in stabilizing Zn anodes.

Biosensors that can automatically and continuously track fluctuations in biomarker levels over time are essential for real-time sensing in biomedical and environmental applications. Although many electrochemical sensors have been developed to quickly and sensitively monitor biomarkers, their sensing stability in complex biofluids is disturbed by unavoidable nonspecific adhesion of proteins or bacteria. Recently, various substrate surface modification techniques have been developed to resist biofouling, yet functionalization of electrodes in sensors to be anti-biofouling is rarely achieved. Here, we report an integrated three-electrode system (ITES) modified with a “liquid-like” polydimethylsiloxane (PDMS) brush that can continuously and stably monitor reactive oxygen species (ROS) in complex fluids. Based on the slippery “liquid-like” coating, the modified ITES surface could prevent the adhesion of various liquids as well as the adhesion of proteins and bacteria. The “liquid-like” coating does not significantly affect the sensitivity of the electrode in detecting ROS, while the sensing performance could remain stable and free of bacterial attack even after 3 days of incubation with bacteria. In addition, the PDMS brush-modified ITES (PMITES) could continuously record ROS levels in bacterial-rich fluids with excellent stability over 24 h due to the reduced bacterial contamination on the electrode surface. This technique offers new opportunities for continuous and real-time monitoring of biomarkers that will facilitate the development of advanced sensors for biomedical and environmental applications.