Low Voltage Research Articles

Industrial‐level Paired Electrosynthesis of Valuable Chemicals over a High‐performance Heterostructural Electrode

Paired electrosynthetic technology is of significance to realize the co‐production of high‐added value chemicals. However, exploiting efficient bifunctional electrocatalyst of the concurrent electrocatalysis to achieve the industrial‐level performance is still challenging. Herein, an amorphous Co2P@MoOx heterostructure is rationally designed by in‐situ electrodeposition strategy, which is acted as excellent bifunctional catalysts for the electrocatalytic nitrite reduction reaction (NO2RR) and glycerol oxidation reaction (GOR). The membrane‐electrode assembly (MEA) electrolyzer realizes a low voltage of 1.30 V, robust stability over 200 h at 100 mA cm‐2, high Faraday efficiencies and yield of NH3 (above 95%, 49.7 mg h‐1 cm‐2) and formate (above 95%, 152.3 mg h‐1 cm‐2) at industrial‐level current density of 500 mA cm‐2. In‐situ spectroscopy studies have shown that high‐valence CoOOH is the main active material of GOR, and the main catalytic conversion pathway of NO2RR involves key *NH2OH reaction intermediates. In addition, theoretical calculations confirm that the Co2P@MoOx heterostructure has strong interfacial electronic interaction and optimized reaction energy barriers, which endows its intrinsically high electrocatalytic activity for the co‐electrosynthesis of NH3 and formate.

Low-voltage operation mode of ASCENT-propelled pulsed plasma thruster

This study demonstrates the feasibility of operating a liquid-fed pulsed plasma thruster (PPT) at low voltages, in the magnetoplasmadynamic (MPD) arc range below 100 V, in contrast to conventional PPTs operating in the kV range. The system uses ASCENT (Advanced Spacecraft Energetic Nontoxic Propellant) as a propellant. Low voltage operation was achieved by eliminating long discharge electrodes and associated voltage drops. The designed thruster demonstrated consistent operation at discharge voltages of 50–150 V for discharge currents varying in the range of 2–8 kA. The measured V–I characteristics of the thruster’s discharge were consistent with self-field MPD arcs, and, correspondingly, the designed system can be classified as a pulsed-MPD thruster. We further confirmed the action of the accelerating Lorentz force on the propellant by measuring fast exhaust ion velocities in the range of 10–30 km/s. Photographic observations confirmed the formation of a plasma jet sourced from the ASCENT propellant, with minimal cathode spot formation, supporting that reduced cathode erosion and the system’s long operational lifetime can be expected. The designed ASCENT-propelled PPT can be utilized as an electric propulsion mode in a dual-mode propulsion system combining chemical and electric propulsion modes.

In-situ preparation of NiCo-LDH/NF Electrode for Green Hydrogen Production through Alkaline Water Electrolysis

Hydrogen production through water electrolysis is an eco-friendly pathway for renewable and clean energy conversion and storage, hence developing efficient, affordable, and durable electrocatalysts is essential. In this work, the catalytic activity of Nickel Cobalt Layered double hydroxide (NiCo-LDH) toward overall alkaline water splitting is investigated, and the effect of different ratios of Ni:Co in the LDH structure on the electrochemical performance is studied. NiCo-LDH is in situ prepared and grown directly on the surface of a conductive Nickel Foam (NF) electrode through a hydrothermal method with different molar ratios of both Nickel and Cobalt. The prepared NiCo-LDH/NF samples are then characterized by XRD, FTIR, SEM and XPS analyses to confirm the formation of the LDH structures. Then, the electrochemical performance was evaluated using the common electrochemical techniques of cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Results show that 1Ni:2Co-LDH/NF is the optimum molar ratio for Hydrogen Evolution Reaction (HER), while 2Ni:1Co-LDH/NF is the optimum molar ratio for Oxygen Evolution Reaction (OER). The synthesized 1Ni:2Co-LDH/NF electrode is found to exhibit an overpotential of 253 mV at 10 mA cm-2 with Tafel slop of 65 mV/dec for HER and 2Ni:1Co-LDH/NF electrode exhibited an overpotential of 273 mV at 10 mA cm-2 with Tafel slop of 38 mV/dec for OER in 1.0 M KOH. To attain a current density of 10 mA/cm2, a low cell voltage of 1.68V is required for water splitting process with 1Ni:2Co-LDH/NF as cathode and 2Ni:1Co-LDH/NF as an anode.

Methodology for Modeling and Correcting the Effects of Extension Cables for Measurements in Low Voltage Grids in the 1.1–10 MHz Frequency Band

Methodology for Modeling and Correcting the Effects of Extension Cables for Measurements in Low Voltage Grids in the 1.1–10 MHz Frequency Band

Which aEEG patterns could predict neurodevelopmental outcome in preterm neonates? - A systematic review.

Amplitude-integrated electroencephalogram (aEEG) enables continuous and simplified bedside monitoring of brain function. This review aims to investigate aEEG's value as a predictor of neurodevelopment outcome in preterm infants. PubMed, Embase and Web of Science were systematically searched according to the PRISMA in April 2023 and updated in October 2023. The protocol was registered on PROSPERO platform and the methodological quality of studies was analyzed using the Newcastle-Ottawa Scale (NOS). Nineteen articles (18 cohort and 1 case-control study) were included, reporting the recording of aEEG in 2074 preterm neonates and its association to neurodevelopment outcome. In most studies, aEEG recording started within 72h of life. The mean NOS score for prospective and retrospective cohort studies were 6 (4-7, median 6) and 6.6 (6-7, median 7), respectively. The case-control study received 7 stars. Burst suppression and low voltage background were associated with poor neurodevelopmental outcome, while normal background and established cyclicity was correlated with a favorable outcome, especially when they occurred in the first week of life. The background patterns and cyclicity of aEEG seems to be reliable patterns to help predict neurodevelopmental outcome in premature infants, especially when monitorization started early.

MOVING FROM VOLTAGE MAPPING TO SCAR MAPPING UTILIZING NOVEL 'NEAR FIELD' METRICS.

In ventricular arrhythmia ablation procedures, traditional voltage mapping calculates overall peak-to-peak measurements. However, this methodology incorporates multiple signal components which do not distinguish near-field versus far-field. To determine how the use of local bipolar measurements as identified by the first derivative of voltage over time (dV/dT) impacts traditional voltage mapping characteristics. Percutaneous endocardial and epicardial electroanatomic mapping was performed in a porcine myocardial infarction model (n=5) utilizing a multipolar and a point-by-point catheter. Electrograms were examined offline based on standard bipolar and unipolar voltage values, and then re-analyzed using a novel algorithm which measures only the voltage magnitude pertaining to the maximum absolute dV/dT within a given electrogram. Computed tomography, gross pathology and histopathology were examined. There were 25,114 bipolar mapping points across multipolar catheter maps and 6,317 mapping points across point-by-point catheter maps. A difference in calculated voltage occurred in >80% of all mapping points, with all changes using dV/dT methodology resulting in lower bipolar voltage values compared to traditional methods. There was a categorical change in standard voltage (scar, border zone, normal) in >7% of all points. Unipolar voltage calculated using local dV/dT also resulted in a lower value in >90% of all mapping points. Histological examination of discrepant regions revealed patterns of diffuse fibrosis. In a porcine infarct model, the use of dV/dT to identify bipolar voltage results in lower measured values in over 80% of all mapping points compared to traditional peak-to-peak. This methodology may more accurately identify local tissue properties by selection of near-field components within substrates implicated in ventricular arrhythmias.

Ultra High-Density Mapping and Ablation of Localized Micro-Reentrant Tachycardias: Insight From the CHARISMA Registry.

Recent advancements in ultra-high-density mapping (UHDM) featuring automated functionalities have enhanced our understanding of micro-reentrant atrial tachycardias (mAT) circuits and the precise localization of the origin. To evaluate the diagnostic support provided by an automated UHDM algorithm in guiding the ablation of mATs. Consecutive patients eligible for AT ablation in 22 Italian centers were prospectively enrolled. All ATs were comprehensively mapped in either the left or right atrium utilizing the RHYTHMIA mapping system. The LUMIPOINT tool was systematically employed to confirm electrogram fragmentation within this defined area. Among 159 ATs analyzed, 97 (61.0%) were identified as macro-reentrant ATs, 50 (31.4%) as focal ATs and 12 (7.5%) as mATs. Concerning the mAT group, the targeted activity was localized in the anterior wall in 4 cases (33.3%), in proximity to PVs in 3 cases (25%), along the left ridge in 2 cases (16.6%), and at the roof, in the free wall and along the CTI in 1 case (8.3%), respectively. Low voltage areas (< 0.1 mV) were detected in all mAT cases and colocalized with the origin site. Over a median of 288 [248-349] days of follow-up, 5 (3.1%) patients suffered from an AT/AF arrhythmia recurrence: 3 (3.1%) were in the MAT group, 1 (2%) in the focal AT and 1 (8.3%) in the mAT group. A novel automated algorithm for mAT identification, coupled with ORION catheter, enables mAT description and transcatheter ablation of the localized origin of this rare form of AT results in a satisfactory procedural success rate. Catheter Ablation of Arrhythmias With High-Density Mapping System in the Real World Practice (CHARISMA). http://clinicaltrials.gov/ Identifier: NCT03793998.

Advanced visual sensing and control in CMT-based WAAM processes

Wire Arc Additive Manufacturing (WAAM) can flexibly produce high-performance parts that meet the requirements of deep-sea environments, but it has problems with insufficient molding accuracy and surface smoothness, which require improved precision and quality. To address these challenges, this paper establishes a WAAM experimental system based on Cold Metal Transfer (CMT) technology. First, the influence of process parameters on multi-layer single-channel forming was studied. Second, a structured light visual sensing system based on a high-speed camera was developed. Finally, a method for controlling the camera’s triggering mode at low voltage was designed, effectively eliminating arc interference. The experiment extracted and preprocessed the laser stripe ROI (Region of Interest), extracted geometric size information of the weld seam, and then performed median filtering to extract the centerline and feature points. By constructing a CMT-based WAAM monitoring system, high reliability and quality control of the manufacturing process and weld formation have been achieved.

Tuning resistive switching behavior and conduction mechanism in Se80Te20 alloy with Fe, Co, Ni, and Cu additives

Abstract The present investigations comprehensively analyze the current-voltage characteristics and conduction mechanism in Se80Te20 (ST) and Se78Te20TM2 (STTM; where TM denotes transition metals Cu. Fe, Co, and Ni) glasses. This study focuses on a multi-component system and investigates the voltage-current characteristics of nearly identical disc-shaped specimens at various temperatures below their glass transition points. By analyzing the experimental data, we discovered resistive switching phenomena in the parent glass and its ternary variants containing transition metals Fe, Co, Ni, and Cu. Remarkably, the resistive switching behavior of these samples has been observed to be related to the Meyer-Neldel rule. Additionally, our findings reveal space charge-limited conduction in binary and ternary alloys. We identified linear relationships between ln I and V1/2 across both low and high voltage ranges, which we explained using the Poole-Frenkel mechanism. While the I-V characteristics showed ohmic behavior at lower voltages, a transition to non-ohmic behavior at higher voltages was attributed to voltage-induced temperature effects.&amp;#xD;

EXPLORING SINGLE ATOM SUBSTITUTION IN PHENANTHRO[9,10-D]IMIDAZOLE -BASED D-π-A ARCHITECTURES WITH FLUORENE AND ITS HETEROANALOGS FOR NON-VOLATILE RESISTIVE WORM MEMORY DEVICE APPLICATIONS.

A series of D-π-A compounds, with fluorene and its heteroanalogs (carbazole, dibenzofuran, dibenzothiophene) as the donor units and phenanthroimidazole as the acceptor, were designed and synthesized for non-volatile memory device applications. The effect of single-atom substitution on memory behavior was examined through optical, electrochemical, and computational studies. The photophysical studies confirm a significant intramolecular charge transfer from the donor to the acceptor unit, and the electrochemical analysis shows an irreversible anodic peak (0.99-1.21 V) with an optimal band gap ranging from 2.80 to 2.88 eV. All the compounds exhibited non-volatile binary WORM memory behaviour with an ON/OFF current ratio of 105 and 103. The devices also showed excellent stability over 100 cycles and maintained a retention time of 4000 s. Notably, the compound with carbazole substitution displayed a lower threshold voltage and a higher ON/OFF current ratio of 105. Density functional theory calculations confirmed that the combined effects of charge transfer and charge trapping mechanisms are crucial to the resistive switching mechanisms observed. This work highlights the potential of single atom substitution in D-π-A systems, providing valuable insights for designing high-performance data storage devices.

Highly scalable In0.95Ga0.05As based controllable leaky-integrate-fire neuron for high performance spiking neural network and applications

Abstract In this work, we design and simulate a leaky integrate-and-fire (LIF) neuron based on a single Indium Gallium Arsenide (In0.95Ga0.05As) MOSFET. The proposed implementation results in significant improvements in energy, area, and cost reduction. The In0.95Ga0.05As -MOSFET LIF neuron imitates neuron behaviour accurately, with low breakdown voltage, high impact ionization coefficient, and sharp breakdown. Due to the storage of induced holes in the potential well of the In0.95Ga0.05As -MOSFET, impact ionisation is the main mechanism creating the spiking characteristic in this case. It requires only 7.11 pJ/spike of energy, compared to the silicon-based SOI MOSFET, which requires 45 pJ/spike. The LIF neuron exhibits a 0.5 MHz high spiking frequency, which is 5 times higher than real nerves in the human body. Compared to biology, MHz operation provides appealing hardware acceleration. In0.95Ga0.05As -MOSFET LIF neuron firing may be controlled through the application of gate voltage, which can increase the spiking neural networks (SNN) energy efficiency by causing sparse activity. The effects of gate metal work function, Gallium mole fraction, and temperature on spike current variations are also investigated. This neuron circuit has promising potential for large-scale integration in spiking neural network hardware. Reconfigurable threshold logic gates have been investigated for the proposed neuron in order to implement universal digital logic functions, such as NAND and NOR.

Operando Electro-Oxidation Reconstitution of a Newly Designed 2D Co(II)-MOF on Nickel Foam to Cobalt Oxyhydroxide Nanosheets towards Energy Sustainability: A Holy Grail in Electrocatalytic Water Splitting.

The upsurging of cost-effective de novo electrocatalysts through the operando electro-oxidation approaches holds great promise for the scalable production of green energy in the pursuit of energy sustainability. This work introduces an operando electro-oxidation reconstitution strategy in producing a smart electrocatalyst, cobalt "oxyhydroxide" derived from a newly designed 2D cobalt(II) metal-organic framework (NBU-4) directly grown on nickel foam (NF), NBU-4/NF@CoOOH. The electrocatalyst, NBU-4/NF@CoOOH, exhibits an outstanding overpotential of 76 mV for the hydrogen evolution reaction and 336 mV for the oxygen evolution reaction to achieve a current density of 10 mA/cm2 with remarkable Faradaic efficiencies of 97.1 and 93.4%, respectively, in 1 M aqueous KOH. Unveiling the bifunctionality of NBU-4/NF@CoOOH as the cathode and anode for overall water splitting in 1 M aqueous KOH, a low voltage of 1.65 V was needed to obtain 10 mA/cm2 current density. Nonetheless, NBU-4/NF@CoOOH displayed excellent stability for 12 h as evidenced from the chronopotentiometry recorded at 10 mA/cm2. The outstanding bifunctional electrocatalytic performance and stability of the electrocatalyst for 50 h is attributed to the unique 2D hexagonal nanosheet morphology of NBU-4/NF@CoOOH and the microporous structure with zigzag flow channels of NF, facilitating a faster kinetics through the Co3+ and Ni2+ dual sites synergism.

Resistive switching and synaptic characteristics in ZnO@β-SiC composite-based RRAM for neuromorphic computing

The advancement of neuromorphic computing in resistive random-access memory (RRAM) is crucial for the rapid expansion of artificial intelligence. Conventional metal oxide-based RRAM faces challenges in mimicking synaptic activity, leading to the exploration of new resistive switching (RS) materials. This study introduces a ZnO@β-SiC composite-based RRAM device that exhibits biological synapse-like functionality. The device shows self-compliance and forming-free RS at ∼0.8 V, where it also mimics synaptic responses such as potentiation, depression, and paired-pulse facilitation at low voltage stimuli (∼0.6 V, 40 ms) with learning and forgetting behavior. Moreover, the synaptic plasticity is analyzed through spike rate dependent plasticity, spike number dependent plasticity, and spike time dependent plasticity. Further, the transition from short-term plasticity to long-term plasticity is observed under more training pulses and lower interval stimuli. The observed RS mechanism and synaptic functionalities are explained by the electric field-driven formation and dissolution of conducting filaments of oxygen vacancies. The chemical properties and local electronic structure have been examined by x-ray photoelectron spectroscopy and x-ray absorption spectroscopy. To elucidate the atomistic memristive behavior and the contribution of different electrical parameters in RRAM, detailed conductive atomic-force microscopy and impedance analysis have been carried out.

Mitigation of Pitting on Nitrogen-Doped Niobium Surfaces through Two-Step Electropolishing

Abstract Surface processing of niobium superconducting RF cavities used in particle accelerators is crucial for determining their performance. The nitrogen (N)-doping method, developed at Fermilab, enhances the cavities' quality factor by doping the cavity's interior surface with N atoms at 800°C. After N-doping, electropolishing (EP) is employed to remove the niobium nitride phases and attain the desired concentration of interstitial N atoms. This study explores the effects of EP conditions on N-doped niobium samples. The samples were electropolished at 5 to 40°C and voltages between 3 and 22 V. Different EP voltage ranges produced two types of pits, classified based on their sizes. Larger pits, linked to higher voltages, are also affected by the reaction rate. Pitting could be reduced at a lower temperature and adequate EP voltage. However, to effectively minimize gas evolution forming large-sized pitting, peeling off the top nitride layer before EP might be beneficial. This was achieved through precise low-voltage etching, forming a two-step EP process. The process involves removing the top 100–200 nm layer at a low voltage, followed by standard EP to remove the required material. This two-step EP process effectively mitigated the pitting risk associated with gas evolution on N-doped surfaces.

Volatile MoS2 Memristors with Lateral Silver Ion Migration for Artificial Neuron Applications

Layered 2D semiconductors have shown enhanced ion migration capabilities along their van der Waals (vdW) gaps and on their surfaces. This effect can be employed for resistive switching (RS) in devices for emerging memories, selectors, and neuromorphic computing. To date, all lateral molybdenum disulfide (MoS2)‐based volatile RS devices with silver (Ag) ion migration have been demonstrated using exfoliated, single‐crystal MoS2 flakes requiring a forming step to enable RS. Herein, present volatile RS with multilayer MoS2 grown by metal‐organic chemical vapor deposition (MOCVD) with repeatable forming‐free operation is presented. The devices show highly reproducible volatile RS with low operating voltages of ≈2 V and fast‐switching times down to 130 ns considering their micrometer‐scale dimensions. The switching mechanism is investigated based on Ag ion surface migration through transmission electron microscopy, electronic transport modeling, and density functional theory. Finally, a physics‐based compact model is developed and the implementation of the volatile memristors as artificial neurons in neuromorphic systems is exploredd.

Constructing an Organic-Inorganic Hybrid Solid-Electrolyte Interface In Situ via an Organo-Polysulfide Electrolyte Additive for Lithium-Sulfur Batteries.

Lithium (Li) metal's extremely high specific energy and low potential make it critical for high-performance batteries. However, uncontrolled dendrite growth and an unstable solid-electrolyte interphase (SEI) during repeated cycling still seriously hinder its practical application in Li metal batteries. Herein, we demonstrate a facile and effective approach to fabricate a flexible and robust hybrid SEI layer using two kinds of organo-polysulfides with different sulfur chain lengths [bis(3-(triethoxysilyl)propyl)disulfide (Si-O-2S) and bis(3-(triethoxysilyl)propyl)tetrasulfide (Si-O-4S)] as the additives in the electrolyte. Compared to Si-O-2S, the siloxane and the long sulfur chain in Si-O-4S are conducive to the production of LixSiSy inorganic components on lithium metal surfaces and the formation of an organic-inorganic hybrid stable SEI layer in conjunction with LixSiOy, thereby improving the stability of the SEI layer and inhibiting the growth of lithium dendrites. Specifically, with 10 wt % Si-O-4S as the additive, an excellent cycling lifespan (1400 h) was achieved with a low hysteresis voltage of ∼17 mV at 1.0 mA cm-2 in a Li-Li symmetrical cell. Moreover, the lithium-sulfur battery also exhibits long cycling stability (850 mA h g-1 at 0.5 C after 200 cycles) and good Coulombic efficiency (99.5%). This study provides an electrolyte additive strategy for the Li anode fabricating a stable SEI layer and long cycling batteries.

Power Demand Patterns of Public Electric Vehicle Charging: A 2030 Forecast Based on Real-Life Data

As the adoption of electric vehicles accelerates, understanding the impact of public charging on the power grid is crucial. However, today, a notable gap exists in the literature regarding approaches capable of accurately estimating the expected influence of e-mobility power demand on electrical grids, especially at medium and low voltage levels. To fill this gap, in this study, a procedure is proposed to estimate the power demand patterns of public car parks in a 2030 scenario. To this end, data collected from real-life car parks in Italy are used in Monte Carlo simulations, where probabilistic daily power demand curves are created with different maximum charging powers (from 7.4 kW to ultra-fast charging). The results highlight high variability in the power demand depending on the location and type of car park. City center car parks exhibit peak demand during morning hours, linked to commercial activities, while car parks near railway stations and hospitals show demand patterns aligned with transportation and healthcare needs. Business area car parks, in contrast, have a more pronounced demand during work hours on weekdays, with much lower activity during weekends. This study also demonstrates that, in some situations, ultra-fast charging can increase peak power demand from the grid by up to 210%. Given their contribution to the existing literature, the power demand patterns from this research constitute a valuable starting point for future studies aimed at quantitatively assessing the impact of e-mobility on the power system. In addition, they can effectively support decision-makers in optimally designing the e-mobility recharge infrastructure.

Low voltage user power internet of things monitoring system based on LoRa wireless technology

The operational efficiency of the current smart grid system is seriously affected by the stability of the operating system, and Internet of Things technology has good applicability in power grid information perception. This study uses LoRa technology to construct a monitoring system for the electric energy Internet of Things. Additionally, an optimization model based on a particle swarm optimization algorithm and backpropagation neural network for optimizing base station positioning and channel quality evaluation is proposed. In addition, a multi-channel adaptive frequency hopping technology has been developed. The experimental results showed that the adaptive frequency hopping technology of the system could complete frequency switching within 2 min, which was more efficient than the traditional sampling and statistical technology that took 4 min. In terms of coverage, the research method had a coverage radius of 25 km, which was superior to other communication technologies such as NB IoT and ZigBee. In terms of data transmission success rate, the research method achieved 98.11%, significantly higher than Sigfox’s 90.02%. In addition, the system had a latency of only 150ms and low power consumption. In summary, the PSO-BP LoRa model proposed in the study has high application value in smart grids and industrial environments, providing technical support for wide-area, low-power, and high-stability Internet of Things monitoring systems.

Cation-Vacancy Engineering in Cobalt Selenide Boosts Electrocatalytic Upcycling of Polyester Thermoplastics at Industrial-Level Current Density.

The past decades have witnessed the increasing accumulation of plastics, posing a daunting environmental crisis. Among various solutions, converting plastics into value-added products presents a significant endeavor. Here, an electrocatalytic upcycling route that efficiently converts waste poly(butylene terephthalate) plastics into high-value succinic acid with high Faradaic efficiency of 94.0% over cation vacancies-rich cobalt selenide catalyst is reported, showcasing unprecedented activity (1.477V vs. RHE) to achieve an industrial-level current density of 1.5Acm-2, and featuring a robust operating durability (≈170h). In particular, when combining butane-1,4-diol monomer oxidation (BOR) with hydrogen evolution using the cation vacancy-engineered cobalt selenide as bifunctional catalyst, a relatively low cell voltage of 1.681V is required to reach 400mAcm-2, manifesting an energy-saving efficiency of ≈15% compared to pure water splitting. The mechanism and reaction pathways of BOR over the vacancies-rich catalyst are first revealed through theoretical calculations and in-situ spectroscopic investigations. The generality of this catalyst is evidenced by its powerful electrocatalytic activity to other polyester thermoplastics such as poly(butylene succinate) and poly(ethylene terephthalate). These electrocatalytic upcycling strategies can be coupled with the reduction of small molecules (e.g., H2O, CO2, and NO3 -), shedding light on energy-saving production of value-added chemicals.

Structural Modifications for Tuning Performance and Operational Modes in n-Type Organic Electrochemical Transistors.

Organic mixed ionic-electronic conductors (OMIECs) are crucial in defining the operational modes and performance of organic electrochemical transistors (OECTs). However, studies on the design and structure-performance correlations of small-molecule n-type OMIECs remain scarce. Herein, we designed and synthesized a series of naphthalene diimide (NDI)-based n-type small molecules by extending π-conjugation and increasing the number of electron-withdrawing groups, achieving performance optimization and even changes in operational modes through structural regulations. OECTs based on 4Br-NDI-3EG exhibit a low threshold voltage of -0.022 V, which is the lowest reported for n-type channel materials to date. NDI-DTYA-3EG, synthesized through π-expansion of 4Br-NDI-3EG, maintains a low threshold voltage of -0.041 V and achieves 2 orders of magnitude improvement in electron mobility (1.04 × 10-2 cm2 V-1 s-1) owing to its mixed edge-on and face-on orientation. Specifically, by further increasing the number of electron-withdrawing groups, NDI-DTYM-3EG attains a sufficiently low LUMO energy level (-4.51 eV), enabling a spontaneous reduction in 0.1 M NaCl solution without external bias, thereby achieving self-doping. Consequently, it exhibits n-depletion-mode characteristics with a transconductance value of 287 μS. Moreover, devices made with NDI-DTYM-3EG show exceptional stability, retaining 98% of the initial drain current after 150 min operation. These results provide insights into the understanding and design of n-type mixed ionic-electronic conductor materials.