Journal of Electroanalytical Chemistry最新文献

Benefiting from the simple and low-cost fabrication of the one-step anti-solvent spin-coating process, the perovskite solar cells (PSCs) have a boost development. However, a great number of defects are generated during solution-fabrication process, retarding the development of PSCs seriously. In this study, the utilization of 4,5-dicyanoimidazole (DCI) as an additive for perovskite precursor solution was investigated. The presence of the double –CN groups in DCI facilitated the formation of Lewis acid-base coordination with unsaturated Pb²⁺ ions, as well as interaction with I^- anions by the –NH- moiety, resulting in the enhanced perovskite film crystallinity, the reduced grain boundaries, and a significant reduction in the defects density of the perovskite film. The decreased trap-assisted recombination and voltage open circuit (V_OC) losses in the PSC resulted in the improved photovoltaic performance of device treated by DCI molecule, the PCE increased from 19.59 % to 21.87 % significantly. Moreover, the unencapsulated device with DCI additive exhibited a remarkable 87.8 % retention of its initial PCE after exposure under 10–20 % relative humidity for 60 days, demonstrating an excellent stability than control device.

Organic electrode materials have been regarded as sustainable alternatives for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, large reserves and wide sources from biomass. However, the variety of presently reported organic electrode materials is very limited and their essential electrochemical sodium storage behaviors also deserve further investigating. In this paper, we explore the electrochemical sodium storage behavior of a conjugated aromatic acid (4,4′-biphenyldicarboxylic acid, H₂bpdc) in esters and ethers-based electrolytes. The results illustrate that in esters-based electrolytes, H₂bpdc just shows limited capacity and poor electrochemical sodium storage kinetics. By contrast, in ethers-based electrolytes, H₂bpdc experiences a process similar to conversion type mechanism from pristine acid to sodium salt, displaying fast kinetics and delivers a high reversible capacity of 280 mA h g⁻¹. This research would provide basic and novel insights to the electrochemical sodium storage behaviors of promising organic electrode materials and accelerate the new materials exploration process for SIBs.

In view of the unquestionable necessity for rapid and accurate analysis of drug molecules to monitor patient overdose, numerous nanosensor-based technologies have been developed in addition to quality control of pharmaceutical manufacture and drug administration. In this regard, sensitive detection of a potent anticancer agent, nelarabine (NEL) was examined at the bare and modified glassy carbon electrode (GCE) with the help of differential pulse (DP) and cyclic voltammetry (CV) techniques. A unique and highly effective nanosensor was developed using a combination of bismuth (III) oxide nanoparticles (Bi₂O₃NPs), silver nanoparticles (AgNPs), and electrochemically reduced graphene oxide (ErGO) onto the GCE surface. The modified Bi₂O₃NPs-AgNPs-ErGO/GCE was characterized by scanning electron microscopy (SEM), CV, and electrochemical impedance spectroscopy (EIS) investigations. Influences of various parameters viz., loading of Bi₂O₃NPs, AgNPs, and GO on the modified GCE, electrolyte pH (PBS 7.0), accumulation potential (–0.2 V), and time (60 s), and scan rate (50 mV s⁻¹) were optimized for NEL response. An enhancement in the current responses toward the oxidation of NEL was observed with the Bi₂O₃NPs-AgNPs-ErGO/GCE compared to that noticed with bare GCE. The modified GCE affirmed high sensitivity, low limit of detection (LOD), excellent reproducibility, repeatability, and storage stability that clearly indicated the effective accuracy of the developed nanosensor. The linear behavior in the concentration range was found to be 0.02–1.0 µM, with LOD values of 0.003 nM in PBS 7.0 and 0.065 nM in serum samples. The electrochemical mechanism of NEL at the bare and modified GCEs were revealed as diffusion-controlled and adsorption-controlled mechanism processes, respectively. The linear calibration curves at both the bare and modified GCEs were noticed for increasing NEL concentrations, as constructed from the DPV measurements. Applications of the Bi₂O₃NPs-AgNPs-ErGO/GCE for NEL detection in pharmaceutical dosage form and human serum sample showed well-accepted recovery results of 98–99 %. The effect of interfering agents was checked on the selectivity of the developed method, and the modified electrode was found to be selective toward NEL in the presence of these interfering agents.

Iridium complexes have been considered as potential promising electrochemiluminescent (ECL) reagents in recent years. However, the instability of ECL signal and easy leaching from the electrode severely limit their applications. In this work, iridium complex doped zinc oxide (ZnO) nanocomposites (Ir@ZnO) were synthesized, which could not only increase the loading amount of iridium complex, but also improve the stability of ECL signal. A sensitive ECL sensor for the detection of phenylalanie (Phe) was proposed via the host–guest recognition of cucurbit[8]uril (Q[8]) and Phe with Ir@ZnO nanocomposites as a signal probe. Q[8] was combined with Ir@ZnO nanocomposites via coordinate bond between carbonyl group of Q[8] and Ir and Zn atoms, which could quench the ECL intensity due to the accommodating ability of Q[8] for dissolved oxygen. In the presence of Phe, Q[8] could be released from the electrode surface through the strong host–guest interaction, and the ECL intensity was restored. The ECL system performed high sensitivity and low detection limit, indicating that the proposed ECL strategy was suitable for the detection of amino acids. Moreover, this work provided a new avenue for the application of water insoluble Ir complexes in ECL sensing field.

Most of proteins in the commercial ELISA kits are recombinant with hexahistidine (His₆) tags. Based on this fact, we proposed a simple procedure for the preparation of signal labels and the design of competitive immunosensors. The signal labels were fabricated through the high-affinity interaction between the His₆ tails on the surface of recombinant proteins and the coordinatively unsaturated copper ions on the surface of pristine Cu-based metal organic framework (Cu-MOF). The recombinant protein-modified MOF could be captured by the sensor electrode, thus producing a strong differential pulse voltammetry signal through the electrochemical reduction of Cu²⁺ ions in MOF. However, the target protein in sample solution could compete with the His₆-tagged protein on the surface of Cu-MOF to bind the antibody attached on the electrode, thus leading to the decrease in the electrochemical signal. The peak current showed an inversely relationship with the concentration of target protein. The competitive immunosensor exhibited a linear range of 1 pg/mL to 1 ng/mL with SARS-CoV-2 nucleocapsid protein (N-protein) as the target analyte. We believe that the method can be used to detect other proteins by utilizing the characteristic of recombinant proteins in commercial kits.

Developing highly active, durable, and non-noble electrocatalysts for water-splitting is critical for efficient renewable energy conversion. Nickel-iron layered double-hydroxide (NiFe-LDH) materials show potential in achieving good catalytic performance, however, which was restricted by the scarce active sites and poor conductivity. Herein, we report a series of NiFe-LDH-based materials of expanded interlayer spacing constructed through S/N co-doping with rich active sites, used as a high-efficient bifunctional electrocatalyst for the oxygen and hydrogen evolution reactions (OER and HER). The experimental results indicate that the intercalation/decoration on the interlayer structure of NiFe-LDH can efficiently reduce the energy barrier and accelerate reaction kinetics. Combining with the structural advantages, including the expanded lattice spacing and exposed active surface sites, the resulting S-N/NiFe-LDH anchored in nickel foam (NF) drives an alkaline electrolyzer with a cell voltage of 1.67 V at a current density of 100 mA cm⁻², as well as robust stability over 100 h, which is much superior to the state-of-the-art Pt/C-RuO₂ electrocatalysts.

An antibody-free molecularly imprinted photoelectrochemical sensor was developed for alpha-fetoprotein (AFP) detection by means of difunctional polydopamine-based molecular imprinting polymers (PDA-MIP) on CdS nanoparticle-decorated ZnO nanorod arrays (CdS@ZnO NAs). Among them, the heterostructured CdS@ZnO NAs could accelerate the spatial separation of electron-hole pairs; while PDA-MIP not only provided abundant target recognition sites without expensive antibody, but also further increase the systemic photocurrent due to the enhanced light absorption capacity. After removing template molecules from PDA-MIP, the resulting imprinted cavities could be occupied by target AFP, leading to a decreased photocurrent. Moreover, the prepared sensor had a wide linearity in the range from 1 pg mL⁻¹ to 1000 ng mL⁻¹ with a low detection limit of 0.38 pg mL⁻¹, as well as excellent selectivity and good stability. The application of AFP analysis in real human serum was also achieved, and the recoveries ranged from 99.2% to 105.2%.

Vanadium pentoxide, as a low-cost, safe and reliable cathode electrode material. Its structure is prone to collapse during the process of repeated Zn²⁺ intercalation and deintercalation of aqueous zinc-ion batteries (AZIBs), so enhancing the structural stability of vanadium pentoxide and improving the rate performance has always been a challenge. In this work, sea urchin-like Na_xV₂O₅ vanadate materials are obtained by solvothermal reaction, and the prepared samples exhibit a fast ion transport path during the process of Na⁺ chemical embedding in V₂O₅ framework, which is due to the plentiful active sites that nanowires can provide. This paves the way for high magnification performance. In addition, the unique sea urchin-like morphology with a large specific surface can continuously adapt to strain during ion insertion to obtain excellent long cycle performance. The above merits endow NaVO with a highly stable discharge capacity of 250.5 mA g⁻¹ at 0.5 A/g and a long cycle capacity of 100 mA h g⁻¹ maintains for more than 11,000 cycles at 10 A/g. Remarkably, the capacity retention rate up to 85.7%.

Effective adjustment of structure and interface charge transfer ability of composite electrode materials are the key to improve the electrochemical performance of the zinc-ion capacitor. Herein, a novel 3D birdcage-like architecture composed of interactive carbon nanotube (CNT) network confining ZIF-67 is prepared though the infiltration–coating strategy, followed by a photo-assisted method to reinforce the coupling interaction between ZIF-67 and CNTs, which is directly used as an cathode of zinc-ion capacitors (ZICs). In terms of this composite, the birdcage-like structure with abundant voids facilitates the ionic/electrolyte transport and buffers the shrinkage/expansion of pseudocapacitive ZIF-67 during intercalation–conversion–deintercalation reactions. Moreover, the robust connection between the ZIF-67 and CNTs can effectively prevent structural deterioration and ensure the ion/electron transport between ZIF-67 and CNTs, thus resulting in a high Zn ion diffusion coefficient, which synergistically guarantees the rate capability and cyclic stability of ZICs. Consequently, the ZICs exhibit a high specific capacitance of 142.33F g⁻¹ (0.5 A/g) and a high energy density of 44.5 Wh kg⁻¹ (375 W kg⁻¹). Furthermore, the ZICs shows excellent cycling stability (92.5% capacitance retention after 5000 cycles at a current density of 0.5 A/g). Our work provides a novel design tactic to enhance the storage properties of zinc ions.

P-type metal oxide semiconductor CuBi₂O₄ exhibits excellent energy band structures and photoelectric response characteristics, which are critical for photoelectrocatalytic water splitting. However, the photocurrent densities are still well below the theoretical limit due to poor charge carrier separation and transport properties. In this work, we report a synthetic method for the preparation of phase-pure CuBi₂O₄ photocathode films via spray pyrolysis by adjusting the evaporation rate of the atomized droplets. An increase in the evaporation rate of the solvent may fix the structure of the deposited film faster and decrease the time available for the establishment of the segregation gradient, thus producing phase-pure semiconductor films. This method reduces process complexity and cost, and the applicability of spray pyrolysis for the preparation of phase-pure CuBi₂O₄ films is also confirmed. In addition, the photoelectrochemical evaluation of the samples prepared under different treatment conditions reveals that hole transport critically affects the photoelectrocatalytic performance of CuBi₂O₄ photocathodes. CuO can be used as a hole transport layer to promote the collection and transfer of holes and reduce the recombination of photogenerated carriers.