Electrochemical Energy Generation Research Articles

Electrodeposited NiB Films as Bifunctional Electrocatalysts in Alkaline Water Electrolizer

Abstract Sustainable electrochemical energy generation requires cost-effective, noble-metal-free electrocatalysts for hydrogen and oxygen production in electrolyzers. This study used electrodeposition to create crystalline NiB films with different boron (B) contents—Ni-B(1.17 wt.%), Ni-B(1.06 wt.%), Ni-B(0.94 wt.%), and Ni-B(0.89 wt.%)—on FTO substrates. These films were tested as bifunctional electrocatalyst electrodes for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline media. The NiB films' composition and morphology were analyzed using SEM, AFM, XRD, GD-OES, and XPS. Linear sweep voltammetry assessed their electrocatalytic performance. Higher B content in the films promoted the formation of electroactive NiOOH, enhancing the OER. The Ni-B(1.17 wt.%) electrode required an overpotential of 380 mV to reach 10 mA cm⁻² for OER, while the Ni-B(1.06 wt.%) electrode required 146 mV for the same current density for HER. An alkaline water electrolyzer using Ni-B(1.17 wt.%) as the anode and Ni-B(1.06 wt.%) as the cathode achieved a current density of 10 mA cm⁻² at 1.71 V for overall water splitting. The system showed stability over 12 hours of testing. The results indicate that NiB films on FTO substrates are promising, low-cost bifunctional electrocatalysts for alkaline water electrolysis, offering an alternative to noble-metal-based electrocatalysts.

Electrochemical Energy Generation by Reusing Domestic Gray Water

Electrochemical Energy Generation by Reusing Domestic Gray Water

Facile fabrication of SnO2/MnTe nanocomposite as an efficient electrocatalyst for OER in basic media

There is a strong demand for developing an extremely effective and robust electrocatalyst to facilitate oxygen evolution reaction in water electrolysis applications. Herein, we successfully produced SnO2/MnTe using an efficient ultrasonication technique that is cost-effective and readily accessible along with improved catalytic behavior. The physical properties of fabricated catalysts are examined to analyze textural, structural and morphological characteristics. The SnO2/MnTe nanocomposite exhibited the low overpotential (181 mV) at 10 mA cm−2 and smaller Tafel slope of 33 mV dec−1 in alkaline (1.0 M KOH) medium. Moreover, the material also showed prolonged and excellent stability over 50 h following 5000 stability cycles. Electrochemical impedance spectroscopy studies demonstrated that charge transfer kinetics at the catalyst-electrolyte interface could be achievable, with lower Rct values (0.8Ω) directing it to increase electrochemical behavior. The acquired outcomes obtained from electrochemical activity demonstrate the potential of SnO2/MnTe as a highly promising electrocatalyst for future electrochemical energy generation.

Enhanced hydrogen evolution and symmetric supercapacitor performance of a Ru-doped multiphase WS2 electrode

The metallic and semiconductive phase (1T/2H) coupling enhanced electrochemical energy generation and storage performance of the Ru-doped WS2 multifunctional electrode is reported here.

Synergistic effect of a bamboo-like Bi2S3 covered Sm2O3 nanocomposite (Bi2S3-Sm2O3) for enhanced alkaline OER.

The availability of hydrogen energy from water splitting through the electrocatalytic route is strongly dependent on the efficiency, durability, and cost of the electrocatalysts. Herein, a novel Bi2S3-covered Sm2O3 (Bi2S3-Sm2O3) nanocomposite electrocatalyst was developed by a hydrothermal route for the oxygen evolution reaction (OER). The electrochemical properties were studied in 1.00 mol KOH solution after coating the target material on the stainless-steel substrate (SS). Physical analysis via XRD, FTIR, IV, TEM/EDX, and XPS revealed that the Bi2S3-Sm2O3 composite possesses metallic surface states, thereby displaying unconventional electron dynamics and purity of phases. The Bi2S3-Sm2O3 composite shows outstanding OER activity with a low overpotential of 197 mV and a Tafel slope of 74 mV dec-1 at a 10 mA cm-2 current density as compared to pure Bi2S3 and Sm2O3. Meanwhile, the composite catalyst retains high stability even after 100 h of the chronoamperometry test. Thus, this work unveils a new avenue for the speedy flow of electrons, which is attributed to the synergetic effect between Bi2S3 and Sm2O3, as well as enriched interfacial defects, which exhibit greater oxygen adsorption capability with improved electronic assemblies in the active interfacial region. In addition, the introduced porous structure in core-shell Bi2S3-Sm2O3 provides extraordinary electrical properties. Thus, this article offers a realistic framework for electrochemical energy generation.

A non-corrosive bifunctional electrocatalyst based on titanate sheet for oxygen reduction and hydrogen evolution reactions

The development of suitable catalysts and catalyst supports is critical in the electrochemical energy generation methods. Herein, a titanate nanosheet-based catalyst support is synthesized and investigated for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). In an in situ single-step hydrothermal method, Pd nanoparticles were anchored onto sodium titanate nanosheet, which imparts excellent stability and methanol tolerance, suggesting its suitability as the cathode catalyst in direct methanol fuel cells. The electrocatalyst also demonstrated high efficiency towards electrochemical and photoelectrochemical hydrogen evolution reactions with an overpotential of −0.29 V and −0.20 V, respectively.

Novel High Conductive Ceramic Materials Based on Two-Layer Perovskite BaLa2In2O7.

The tasks of quality environmental improvement and the development of new energy sources are very relevant. Hydrogen-operating electrochemical devices are strongly needed innovative ceramic materials with target properties, one of which is a high level of proton conductivity. It this paper, the possibility of proton conductivity in acceptor-doped two-layer compositions based on BaLa2In2O7 was proved for the first time. It was proved that doping leads to an increase in conductivity values up to ~1.5 orders of magnitude. The most conductive is the BaLa1.9Sr0.1In2O6.95 composition which demonstrates protonic conductivity value 2 × 10-5 S/cm at 450 °C. The acceptor-doped two-layer perovskites is a novel prospective class of proton-conducting materials, and further modification of their composition opens up a new method for the design of electrochemical energy generation devices.

Vanadium Carbide (V4C3) MXene as an Efficient Anode for Li-Ion and Na-Ion Batteries.

Li-ion batteries (LIBs) and Na-ion batteries (SIBs) are deemed green and efficient electrochemical energy storage and generation devices; meanwhile, acquiring a competent anode remains a serious challenge. Herein, the density-functional theory (DFT) was employed to investigate the performance of V4C3 MXene as an anode for LIBs and SIBs. The results predict the outstanding electrical conductivity when Li/Na is loaded on V4C3. Both Li2xV4C3 and Na2xV4C3 (x = 0.125, 0.5, 1, 1.5, and 2) showed expected low-average open-circuit voltages of 0.38 V and 0.14 V, respectively, along with a good Li/Na storage capacity of (223 mAhg−1) and a good cycling performance. Furthermore, there was a low diffusion barrier of 0.048 eV for Li0.0625V4C3 and 0.023 eV for Na0.0625V4C3, implying the prompt intercalation/extraction of Li/Na. Based on the findings of the current study, V4C3-based materials may be utilized as an anode for Li/Na-ion batteries in future applications.

Filter paper membrane based microfluidic fuel cells: Toward next-generation miniaturized and low cost power supply

Micro Fuel cells or microfluidic fuel cells (μMFCs) are one of the most promising power supplies for portable electronics. However, the necessary electrode spacing is required to prevent fuel-crossover and maintain the stable operation, introducing the unavoidable ohmic resistance and retarding the miniaturization. Herein, we propose a novel μMFC device combining the cellulose paper as separator, with selective catalysts at the cathode side to eliminate the unwanted side reactions and increase the system compactness. One single reactant solution containing fuel and electrolyte is applied to keep the device stable operation. The power-generation properties are evaluated in typical alkaline conditions. A great construction simplification makes the device a substantial high-power density of 2.14 W cm−3 and maximum current density of 15.82 A cm−3. The μMFC stacks are arranged in series and parallel manners, which delivers a maximum power output of 23.6 mW and current of 194.6 mA. It is expected that innovative and customizable performance from commercial paper and low-cost carbonaceous catalysts can provide a forum for future advancement in chip-based electrochemical energy generation and storage devices.

Recent Advances in Nanoscale Based Electrocatalysts for Metal-Air Battery, Fuel Cell and Water-Splitting Applications: An Overview.

Metal-air batteries and fuel cells are considered the most promising highly efficient energy storage systems because they possess long life cycles, high carbon monoxide (CO) tolerance, and low fuel crossover ability. The use of energy storage technology in the transport segment holds great promise for producing green and clean energy with lesser greenhouse gas (GHG) emissions. In recent years, nanoscale based electrocatalysts have shown remarkable electrocatalytic performance towards the construction of sustainable energy-related devices/applications, including fuel cells, metal-air battery and water-splitting processes. This review summarises the recent advancement in the development of nanoscale-based electrocatalysts and their energy-related electrocatalytic applications. Further, we focus on different synthetic approaches employed to fabricate the nanomaterial catalysts and also their size, shape and morphological related electrocatalytic performances. Following this, we discuss the catalytic reaction mechanism of the electrochemical energy generation process, which provides close insight to develop a more efficient catalyst. Moreover, we outline the future perspectives and challenges pertaining to the development of highly efficient nanoscale-based electrocatalysts for green energy storage technology.

Enriched Pyridinic Nitrogen Atoms at Nanoholes of Carbon Nanohorns for Efficient Oxygen Reduction

Nitrogen (N)-doped nanostructured carbons have been actively examined as promising alternatives for precious-metal catalysts in various electrochemical energy generation systems. Herein, an effective approach for synthesizing N-doped single-walled carbon nanohorns (SWNHs) with highly electrocatalytic active sites via controlled oxidation followed by N2 plasma is presented. Nanosized holes were created on the conical tips and sidewalls of SWNHs under mild oxidation, and subsequently, the edges of the holes were easily decorated with N atoms. The N atoms were present preferentially in a pyridinic configuration along the edges of the nanosized holes without significant structural change of the SWNHs. The enriched edges decorated with the pyridinic-N atoms at the atomic scale increased the number of active sites for the oxygen reduction reaction, and the inherent spherical three-dimensional feature of the SWNHs provided good electrical conductivity and excellent mass transport. We demonstrated an effective method for promoting the electrocatalytic active sites within N-doped SWNHs by combining defect engineering with the preferential formation of N atoms having a specific configuration.

Flexible freestanding MoS2-based composite paper for energy conversion and storage.

The construction of flexible electrochemical devices for energy storage and generation is of utmost importance in modern society. In this article, we report on the synthesis of flexible MoS2-based composite paper by high-energy shear force milling and simple vacuum filtration. This composite material combines high flexibility, mechanical strength and good chemical stability. Chronopotentiometric charge–discharge measurements were used to determine the capacitance of our paper material. The highest capacitance achieved was 33 mF·cm−2 at a current density of 1 mA·cm−2, demonstrating potential application in supercapacitors. We further used the material as a cathode for the hydrogen evolution reaction (HER) with an onset potential of approximately −0.2 V vs RHE. The onset potential was even lower (approximately −0.1 V vs RHE) after treatment with n-butyllithium, suggesting the introduction of new active sites. Finally, a potential use in lithium ion batteries (LIB) was examined. Our material can be used directly without any binder, additive carbon or copper current collector and delivers specific capacity of 740 mA·h·g−1 at a current density of 0.1 A·g−1. After 40 cycles at this current density the material still reached a capacity retention of 91%. Our findings show that this composite material could find application in electrochemical energy storage and generation devices where high flexibility and mechanical strength are desired.

Power Plants Based on Renewables and Electrochemical Energy Storage and Generation Systems for Decentralized Autonomous Power Supply

Power Plants Based on Renewables and Electrochemical Energy Storage and Generation Systems for Decentralized Autonomous Power Supply

Highly active N,S co-doped hierarchical porous carbon nanospheres from green and template-free method for super capacitors and oxygen reduction reaction

Abstracts Heteroatom doped carbon materials have been emerging as active materials for electrochemical energy generation and storage. The activity of such carbon materials is strongly depended the specific molecular structure of selected precursors and their synthetic strategy. Herein, we report an efficient bifunctional N, S co-doped carbon nanosphere(NS/C) via pyrolysis of poly (2,6-Diaminopyridine) spheres as precursor for the first time, in which 2,6-Diaminopyridine was polymerized in water using ammonium persulfate as both initiator and sulfur source in the absence of templates and surfactants. The resultant NS/C exhibits uniformly spherical structure filled with hierarchical pores, outstanding electronic conductivity and highly effective doping content of N(4.02 at%) and S(0.87 at%) elements. Electrochemical measurements demonstrate that the NS/C not only exhibits outstanding specific capacitance of 800 F/g in 6.0 M KOH and 710 F/g in 1.0 M H2SO4, but also displays excellent catalytic performance for oxygen reduction reaction (ORR) with the onset potential at 1.01 V vs RHE and the half-wave potential at 0.85 V vs RHE in 0.1 M KOH, outperforming the activity of carbon materials previously reported. The superior electrochemical properties of NS/C is directly attributed to the synergetic effect of N,S co-doping and its excellent conductivity, accessibility, high specific surface area as well as hierarchical pore structure.

Accelerating the oxygen reduction reaction via a bioinspired carbon‐supported zinc electrocatalyst

Oxygen utilization in electrochemical energy generation systems requires to overcome the slow kinetics of oxygen reduction reaction (ORR). Herein, we have outstretched an efficient strategy in order for developing a bioinspired Zn (N4)/sulfur/graphitic carbon composite (Zn‐S‐Gc) with an effective performance for the ORR at low temperature. The catalyst composite was created by attaching the Zn (N4) centers in the form of zinc phthalocyanine on the sulfur‐linked graphitic carbon surface. The most positive ORR onset potential of about 1.00 V versus a reversible hydrogen electrode (RHE) was obtained due to the unique structure of a new catalyst in KOH solution (pH = 13) at low temperature (T = 298 K). The catalyst was evaluated using the rotating‐disk electrode method in the potential range of −0.02–1.18 V versus RHE. The number of transferred electrons as one of the most important parameters (n > 3.70) is almost constant in a wide range of low overpotentials (0.1–0.6 V), which indicates a more efficient four‐electron pathway from O2 to H2O on the catalyst surface. The estimated Tafel slope in an appropriate range is about ≈ −133.3 mV/dec at a low current density and E1/2 of the electrocatalyst displays a negative shift of only 11 mV after 10,000 cycles. The mean size of the catalyst centers is on the nanoscale (<50 nm).

A\xa0surface-modified antiperovskite as\xa0an electrocatalyst for water oxidation

An efficient and cost-effective oxygen evolution reaction (OER) electrocatalyst is key for electrochemical energy generation and storage technologies. Here, the rational design and in situ formation of an antiperovskite-based hybrid with a porous conductive Cu1−xNNi3−y (x and y represent defect) core and amorphous FeNiCu (oxy)hydroxide shell is reported as a promising water oxidation electrocatalyst, showing outstanding performance. Benefiting from the unique advantage of core–shell structure, as well as the synergistic effect of Fe, Ni, and Cu and the highly porous hierarchical structure, the hybrid catalyst exhibits highly efficient and robust OER performance in alkaline environments, outperforming the benchmark IrO2 catalyst in several aspects. Our findings demonstrate the application potential of antiperovskite-based materials in the field of electrocatalysis, which may inspire insights into the development of novel materials for energy generation and storage applications.

A Hybrid Power Plant Based on Renewables and Electrochemical Energy Storage and Generation Systems for Decentralized Electricity Supply of the Northern Territories

A Hybrid Power Plant Based on Renewables and Electrochemical Energy Storage and Generation Systems for Decentralized Electricity Supply of the Northern Territories

Effects of Reaction Conditions on Electroreduction of Biomass-Derived Furfural and Its Side Reactions in Acidic Electrolyte

Current investigations for electrochemical energy storage and generation systems help to dramatically decrease the demand for traditional fossil fuels. However, organic carbon resources, also, need to be replaced with alternatives to totally reduce their demands. In this respect, biomass is a promising sustainable resource for both alternative fuels and organic carbon-based materials [1]. Furfural (FF) is a lignocellulose-derived C­5 chemical platform that can be converted to furfuryl alcohol (FA) and 2-methyl furan (MF), which are an adhesive intermediate and a promising fuel candidate, respectively [2]. Traditionally, catalytic hydrogenation and hydrogenolysis (CH) is used for the conversion of FF to FA and MF, but it requires externally supplied hydrogen gas, high pressure and high temperature for the reaction[1, 2]. In contrast, electrochemical hydrogenation and hydrogenolysis (ECH) facilitates the conversion of FF at ambient conditions with no H2 gas. ECH of FF can use atomic hydrogen, supplied from the aqueous electrolyte. These advantages led to emerging studies for ECH of biomass, but it has not been broadly studied [3]. The relationships between electrochemical reaction conditions and results will greatly contribute to broadening the ECH of FF. In our previous study, FA and MF yield increased as a current density increased when the equivalent amount of charge was applied to the reaction in acidic solutions [4]. Also, we found that furanic compounds participate in homogeneous side reactions in pH ≤ 1 solution that can decrease mole balance and products yield as reaction time increase [4]. Another concurrent side reaction that undesirably consumes electrons is the hydrogen evolution reaction[5]. Here, we focus on the effects of applied potentials and Cu electrocatalysts, combined with rapid evaporation of MF, produced from ECH of FF. This is to investigate the product yield and electrochemical efficiency for products as well as side reactions at multiple applied potentials in 0.5 M sulfuric acid (pH 0). Also, rapid evaporation of MF with N2 gas flowing is used for avoiding its homogeneous side reactions at pH 0 [4]. Bare Cu foil and micro-sized Cu supported on Cu have been used as electrocatalysts. Rapid N2 gas flowing enhanced the mole balance and MF yield. FF conversion and MF yield increased when applied potential increased, but electrochemical efficiency for FA and MF production increased as applied potential decreased. Micro-sized Cu electrocatalysts had higher conversion of FF and yield of MF than bare Cu foil. [1] G.W. Huber, S. Iborra, A. Corma, Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering, Chemical Reviews, 106 (2006) 4044-4098. [2] Y. Nakagawa, M. Tamura, K. Tomishige, Catalytic reduction of biomass-derived furanic compounds with hydrogen, ACS Catalysis, 3 (2013) 2655-2668. [3] Y. Kwon, K.J.P. Schouten, J.C. van der Waal, E. de Jong, M.T.M. Koper, Electrocatalytic conversion of furanic compounds, ACS Catalysis, 6 (2016) 6704-6717. [4] S. Jung, E.J. Biddinger, Electrocatalytic hydrogenation and hydrogenolysis of furfural and the impact of homogeneous side reactions of furanic compounds in acidic electrolytes, ACS Sustainable Chemistry & Engineering, 4 (2016) 6500-6508. [5] R. Parsons, The rate of electrolytic hydrogen evolution and the heat of adsorption of hydrogen, Transactions of the Faraday Society, 54 (1958) 1053-1063.

In Operando X-Ray Imaging and Tracking of Degradation and Failure Phenomena inside Zinc-Air Systems

In search for the next generation of battery technology, rechargeable aqueous zinc-air systems present very attractive power sources due to high specific energy, safety, environmental compatibility and low cost of components and active materials. Nonetheless these systems have not yet been commercialised as they suffer from a short cycle life that prohibits their use for large electrical storage applications that require thousands of deep discharge cycles. One of the key factors responsible for shortened cycle life is dendritic growth occurring during the system charge. Dendrites can grow sufficiently wide to cause an internal short-circuit between the anode and the cathode. While extensive work has been carried out to study and mitigate zinc dendrite formation; real time dendritic growth mechanisms remain poorly understood X-ray micro/nano tomography methods can provide unique insights into operation, degradation and failure of electrochemical energy storage and generation devices and systems. We implemented synchrotron x-ray tomography to investigate the mechanism and kinetics of dendrite formation and dissolution during zinc-air system operation. The dendrite growth and dissolution was analysed in-operando in radiography mode while three-dimensional characterisation of dendrites on top of the zinc electrode was carried out based on set of reconstructed multiple tomographic projections (Figure 1). Additionally individual dendrites have been analysed by high resolution FIBSEM. As such, an ability to actively track the mechanisms of growth and dissolution of dendrites form a critical basis if we are to extend the cycle life of metal-air batteries. Figure 1

Galvanism of continuous ionic liquid flow over graphene grids

Flow-induced voltage generation on graphene has attracted great attention, but harvesting voltage by ionic liquid continuously flowing along graphene at macro-scale is still a challenge. In this work, we design a network structure of graphene grids (GG) woven by crisscrossed graphene micron-ribbons. The structure is effective in splitting the continuous fluid into “droplets” to generate consistent voltage using the mechanism of electrochemical energy generation. Key parameters such as flow rate, mesh number of GG, and slope angle are optimized to obtain maximum voltage in energy generation. The results suggest great potential of this graphene-based generator for future applications in energy harvesting.