Water Electrolysis Device Research Articles

In Situ Anodic Transition and Cathodic Contamination Affect the Overall Voltage of Alkaline Water Electrolysis

NiFe (oxy)hydroxide has been widely used as a benchmark anodic catalyst for oxygen evolution reactions (OERs) in alkaline water electrolysis devices; however, the energy saving actually takes contributions from both the anodic OER and cathodic hydrogen evolution reaction (HER). In this work, we observe the catalytic promotion upon the in situ-derived NiFe (oxy)hydroxide from the NiFe alloy monolithic electrode and also point out that the coupled nickel cathode is contaminated, leading to the loss of HER activity and a reduction in overall efficiency. It is found that Ni2+ and Fe3+ cations are inevitably detached from the anode into the electrolyte and electrodeposited on the nickel cathode after the three-month industrial simulation. This research presents the significant enhancement of the oxygen evolution catalysis using an in situ aging process and emphasizes that the catalytic application should not only be isolated on the half reaction, but a reasonable coupled electrode match to get rid of the contamination from the electrolyte is also of great significance to sufficiently present the intrinsic catalytic yielding for the real application.

Synergy strategy of multi-metals confined in heteroatom framework toward constructing high-performance water oxidation electrocatalysts

The development of a low-cost, highly active, and non-precious metal catalyst for oxygen evolution reaction (OER) is of great significance. Multi-metallic catalysts containing Fe, Co, and Ni exhibit remarkable OER activity, while the specific contributions of each component and the synergistic effects in the ternary metal catalyst has remained elusive. In this work, we synthesized a series of S and N-doped mono-metallic, bi-metallic, and tri-metallic hollow carbon sphere electrocatalysts (M−SNC) with the goal of enhancing the catalysts OER activity and shedding light on the unique roles and synergistic effects of the various metals in the FeCoNi ternary metal catalyst. Our systematic analyses demonstrated the introduction of Fe effectively reduces the overpotential, Co accelerates the kinetics of OER, and the addition of Ni further improves the OER performance. Benefiting from the synergistic effects, the FeCoNi-SNC exhibits a low overpotential of 270 mV, with no morphological or structural changes after reaction, maintaining high activity for 72 h at 10 mA cm−2. Moreover, the assembled FeCoNi-SNC || Pt/C water electrolysis device operates for 65,000 s with minimal degradation, demonstrating its potential for practical application. This work presents a synergy strategy for the preparation of low-cost and highly efficient OER catalysts and further provides insights into the rational design and preparation of multicomponent catalysts.

Identification of Representative Wind Power Fluctuation Patterns for Water Electrolysis Device Stress Testing: A Data Mining Approach

Identification of Representative Wind Power Fluctuation Patterns for Water Electrolysis Device Stress Testing: A Data Mining Approach

Non-Noble-Metal-Based Electrocatalysts for Acidic Oxygen Evolution Reaction: Recent Progress, Challenges, and Perspectives.

The oxygen evolution reaction (OER) plays a pivotal role in diverse renewable energy storage and conversion technologies, including water electrolysis, electrochemical CO2 reduction, nitrogen fixation, and metal-air batteries. Among various water electrolysis techniques, proton exchange membrane (PEM)-based water electrolysis devices offer numerous advantages, including high current densities, exceptional chemical stability, excellent proton conductivity, and high-purity H2. Nevertheless, the prohibitive cost associated with Ir/Ru-based OER electrocatalysts poses a significant barrier to the broad-scale application of PEM-based water splitting. Consequently, it is crucial to advance the development of non-noble metal OER catalysis substance with high acid-activity and stability, thereby fostering their widespread integration into PEM water electrolyzers (PEMWEs). In this review, a comprehensive analysis of the acidic OER mechanism, encompassing the adsorbate evolution mechanism (AEM), lattice oxygen mechanism (LOM) and oxide path mechanism (OPM) is offered. Subsequently, a systematic summary of recently reported noble-metal-free catalysts including transition metal-based, carbon-based and other types of catalysts is provided. Additionally, a comprehensive compilation of in situ/operando characterization techniques is provided, serving as invaluable tools for furnishing experimental evidence to comprehend the catalytic mechanism. Finally, the present challenges and future research directions concerning precious-metal-free acidic OER are comprehensively summarized and discussed in this review.

(Invited) Perovskite/Perovskite Tandem Photoelectrodes for Unassisted Water Splitting

The bandgap tunability and low-temperature processing make halide perovskites excellent candidates for achieving efficient and cost-effective tandem devices for solar cells and solar-driven water electrolysis devices. Here, we report our progress on fabricating perovskite/perovskite tandem cells consisting of two solution-processed perovskite subcells for unassisted water-splitting applications. The perovskite/perovskite tandem photoelectrodes are achieved by monolithically integrating a wide-bandgap (1.7 – 2.1 eV) Pb-based mixed-halide (Br-I) perovskite top subcell and a narrower-bandgap (1.25 - 1.55 eV) bottom subcell based on Pb-based or mixed Pb-Sn iodide perovskites. Varying the halide perovskite composition for each subcell enables us to tailor the photovoltaic performance of the tandem devices. We demonstrate that perovskite/perovskite tandem solar cells can deliver open-circuit voltages of more than 2 V. The high photovoltage provides a sufficient overpotential to drive unassisted photoelectrochemical (PEC) water splitting with a solar-to-hydrogen conversion efficiency of more than 15%. After applying water-impermeable encapsulants, the perovskite/perovskite photoelectrodes can successfully operate in an aqueous environment and enable a long operational lifetime.

(Invited) Hierarchically Structured Electrocatalysts Using Scalable Synthesis Techniques for Membrane Water Electrolyzers

Beyond composition, the morphology of catalyst particles is a key-parameter to allow for a high accessibility to catalytic sites but it is also of paramount importance to manage gases and water transport within catalyst layers in membrane-electrode assembly based devices. Besides their electrochemical activity, fabricating high performance catalysts and catalyst layers that are compatible with industry fabrication processes is critical for their implementation in commercial electrochemical devices. Considering these requirements, we are developing green, cheap and scalable solution synthesis techniques to prepare hierarchically structured catalysts that can be readily incorporated into catalyst layers.Two strategies will be discussed. We have recently introduced an aerosol synthesis technique for the preparation of highly porous iridium pure and mixed oxides that are highly active and stable towards the Oxygen Evolution Reaction in acidic media. Beside beeing ideally suited for the preparation of highly porous catalyst layers, the hierarchical morphology can also be used for fundamental studies [1] or used as a probe to follow the catalyst degradation in PEM water electrolysis devices.[2]We also implemented the well-known polyol process [3] to prepare heterofunctional catalysts with ultra-low PGM content that are active towards another challenging reaction in anion exchange membrane water electrolyzer: the Hydrogen Evolution Reaction in alkaline media. The structure-properties relationship in these materials is assessed by a large set of techniques including SEM, XRD, XRF and STEM-EDX as well as surface (XPS) and bulk (XAS) characterizations, including operando XAS. Nature Communications, 2021, 12, 3935, 1038/s41467-021-24181-x Chemistry of Materials, 2023, 35, 20, 8590–8598, 1021/acs.chemmater.3c0152. Chem. Soc. Rev. , 2018, 47, 5187-5233, 10.1039/C7CS00777A

Direct Formation of Nifep Catalytic Films on Anion Exchange Membrane As Efficient HER Catalyst for Water Electrolysis Device

Anion exchange membrane water electrolysis (AEMWE) is advantageous in terms of device cost, compared with proton exchange membrane water electrolysis, because non-noble metal-based catalyst in alkaline condition is applicable.1 In AEMWE device, the membrane electrode assemblies (MEAs) plays an important role on the cell performance and stability.2 And the MEAs fabricated by (catalyst-coated-membrane) CCM cathode and (catalyst-coated-substrate) CCS anode is proved to be appropriate configuration.3 In the conventional way, the CCM cathode employs an ionomer/binder to combine the catalyst layer and AEM together, which however suffers the problem of degradation, thus limiting the life time of the device.2 We have reported an electroless deposition process that allows Ni-based metal to be deposited directly on AEM surface, which opens the possibility to fabricate CCM without ionomer/binder.4 In this work, NiFeP films (1 cm × 1 cm in area, ~3 μm in thickness) is electrolessly deposited on Tokuyama A-201 AEM as HER catalyst in room temperature AEMWE device. Electroless deposition method forms NiFeP films on AEM surface without binder, thus avoiding the disadvantage of degradation of the catalyst due to the ionomer/binder. The successfully deposited NiFeP catalyst exhibits outstanding HER performance by delivering -500 mA/cm2 at overpotential of -0.50 V in 1.0 M K2CO3 at room temperature. Furthermore, the NiFeP catalyst shows a good stability by delivering -500 mA/cm2 for at least 20 h without obvious potential loss. The outstanding HER performance of NiFeP should originates from the increased number of active sites caused by porous structure of the interface and the enhanced intrinsic activity caused by the well-tuned electronic structure. A series of characterization would be presented in terms of composition, morphology, phase and electron transfer behavior of the NiFeP films. Our work is hoped to give a new insight of fabrication of MEAs to achieve better performance of AEMWE devices. References R. R. Raja Sulaiman, W. Y. Wong, and K. S. Loh, Intl J of Energy Research, 46, 2241–2276 (2022).Y. Leng et al., J. Am. Chem. Soc., 134, 9054–9057 (2012).H. Ito et al., J Appl Electrochem, 48, 305–316 (2018).T. Fujimura, M. Kunimoto, Y. Fukunaka, H. Ito, and T. Homma, Electrochemistry, 89, 192–196 (2021).

Acidic water oxidation with ultralow 131 mV overpotential over surface-reconstructed RuIr nanoalloy: Chloride-driven high performance

The oxygen evolution reaction (OER) in kinetics is sluggish but a key electrode reaction for various energy storage and conversion devices, such as green hydrogen from water electrolysis, rechargeable metal-air battery, sustainable carbon dioxide electroreduction, synthetic ammonia, etc. However, it still remains a major and cutting-edge challenge to pioneering catalysts with simultaneously ultrahigh activity and stability for OER, even with diverse performance enhancement strategies, such as complex composition designs, surface chemical reconstructions, and multiphase engineering have been implemented to accelerate this key electrochemical process. Herein, we proposed a chloride-triggered activation and stabilization strategy for the branched RuIr alloy coated by thin IrO2 layer to achieve unparalleled high-performance toward OER in acidic water. The ultralow overpotential of the activated catalyst is reduced to about 131 mV at 10 mA cm−2, with 79-fold enhancement of mass-activity than commercial IrO2. Moreover, a modified proton exchange membrane water electrolysis (PEMWE) device was first constructed by introducing NaCl into recyclable electrolyte. It run a stably and low cell potential (1.514 V) for 170 h, having no obvious performance decay at 50 mA cm−2 in 0.5 M H2SO4 with 1.6 M NaCl, which far exceeding traditional IrO2||Pt/C PEMWE. The outstanding performance stems from that Cl- ions enable a faster lattice oxygen evolution mechanism. The novel catalyst activates asymmetric O-Ir-Cl structure induced by Cl- filled oxygen vacancies, which modify the electronic and geometric properties, improving OER activity. Moreover, these adsorbed ions can also efficiently patch and refill the oxygen vacancies that ensure the long-term structure stability. Therefore, tailoring the chloride-activated Ir-based catalysts with simultaneously improved activity and stability may be a valuable guide to achieve surprisingly high-performances for acidic water splitting.

Constructing Built-in-Electric Field for Boosting Electrocatalytic Water Splitting.

Electrocatalytic water splitting shows great potential for producing clean and green hydrogen, but it is hindered by slow reaction kinetics. Advanced electrocatalysts are needed to lower the energy barriers. The establishment of built-in electric fields (BIEF) in heterointerfaces has been found to be beneficial for speeding up electron transfer, increasing electrical conductivity, adjusting the local reaction environment, and optimizing the chemisorption energy with intermediates. Engineering and modifying the BIEF in heterojunctions offer significant opportunities to enhance the electronic properties of catalysts, thus improving the reaction kinetics. This comprehensive review focuses on the latest advances in BIEF engineering in heterojunction catalysts for efficient water electrolysis. It highlights the fundamentals, engineering, modification, characterization, and application of BIEF in electrocatalytic water splitting. The review also discusses the challenges and future prospects of BIEF engineering. Overall, this review provides a thorough examination of BIEF engineering for the next generation of water electrolysis devices.

The hybrid Pt nanoclusters/Ru nanowires catalysts accelerating alkaline hydrogen evolution reaction

Water electrolysis via alkaline hydrogen evolution reaction (HER) is a promising approach for large-scale production of high-purity hydrogen at a low cost, utilizing renewable and clean energy. However, the sluggish kinetics derived from the high energy barrier of water dissociation impedes seriously its practical application. Herein, a series of hybrid Pt nanoclusters/Ru nanowires (Pt/Ru NWs) catalysts are demonstrated to accelerate alkaline HER. And the optimized Pt/Ru NWs (10 ​% wt Pt) exhibits exceptional performance with an ultralow overpotential (24 ​mV at 10 ​mA ​cm−2), a small Tafel slope (26.3 ​mV dec−1), and long-term stability, outperforming the benchmark commercial Pt/C-JM-20 ​% wt catalyst. This amazing performance also occurred in the alkaline anion-exchange membrane water electrolysis devices, where it delivered a cell voltage of about 1.9 ​V at 1 ​A ​cm−2 and an outstanding stability (more than 100 ​h). The calculations have revealed such a superior performance exhibited by Pt/Ru NWs stems from the formed heterointerfaces, which significantly reduce the energy barrier of the decisive rate step of water dissociation via cooperative-action between Pt cluster and Ru substance. This work provides valuable perspectives for designing advanced materials toward alkaline HER and beyond.

Large-Scale and Simple Synthesis of NiFe(OH)x Electrode Derived from Raney Ni Precursor for Efficient Alkaline Water Electrolyzer

Water electrolysis is a crucial technology in the production of hydrogen energy. Due to the escalating industrial demand for green hydrogen, the required electrode size for a traditional alkaline water electrolyzer has been increasing. Numerous studies have focused on developing highly active oxygen evolution reaction (OER) catalysts for water electrolysis. However, there remains a significant gap between the microscale synthesis of catalysts in laboratory settings and the macroscale preparation required for industrial scenarios. This challenge is particularly pronounced in the synthesis of sizable self-supported electrodes. In this work, we employed a commercially available Raney Ni-coated Ni mesh as a precursor material to fabricate a self-supported NiFe(OH)x@Raney Ni anode with a substantial dimension exceeding 300 mm through a straightforward immersion technique. The as-prepared electrode exhibited remarkable electrocatalytic OER activity, as an overpotential of only 240 mV is required to achieve 10 mA cm−2. This performance is comparable to that of NiFe-LDHs synthesized via a hydrothermal method, which is difficult to scale up for industrial applications. Furthermore, the electrode demonstrated exceptional durability, maintaining stable operation for over 100 h at a current density of 500 mA cm−2. The large-scale electrode displayed consistent overpotentials across various areas, indicating uniform catalytic activity. When integrated into an alkaline water electrolysis device, it delivered an average cell voltage of 1.80 V at 200 mA cm−2 and achieved a direct current hydrogen production energy consumption as low as 4.3 kWh/Nm3. These findings underline the suitability of electrodes for industrial scale applications, offering a promising alternative for energy-efficient hydrogen production.

Efficient optimization of electron transfer pathway by constructing phosphide/ceria interface boosts seawater hydrogen production

Developing efficient and durable hydrogen evolution reaction (HER) electrocatalysts is one of the most important issues for the commercialization of seawater electrolysis, but it remains challenging. Here, we report a CeO2-CoP nanoneedle array catalyst loaded on Ti mesh (CeO2-CoP/TM) with work-function-induced directional charge transport properties. The CeO2-CoP/TM catalyst showed superior HER catalytic activity and stability, with overpotentials of 41 and 60 mV to attain 10 mA cm−2, in 1 M KOH and 1 M KOH + seawater electrolyte, respectively. Experimental results and theoretical calculations reveal that the work function drives the charge transfer from CeO2 to CoP, which effectively balances the electronic density of CoP and CeO2, optimizes the d-band center, and accelerates the water activation kinetics, thus enhancing the HER activity. The solar-driven water electrolysis device displays a high and stable solar-to-hydrogen conversion efficiency of 19.6%. This study offers a work function-induced directional charge transport strategy to design efficient and durable catalysts for hydrogen production.

Optimizing the Dehydrogenation Kinetics of Metal Nitrides for Energy‐Efficient Seawater Hydrogen Production at 2 A cm−2

AbstractSeawater hydrogen production, vital for sustainable energy solutions and freshwater preservation, faces challenges due to seawater complexity and high energy consumption. A strategy to modulate dehydrogenation kinetics of dual‐phase metal nitrides using low‐loaded Pt quantum dots (QDs), achieving stable and energy‐efficient hydrogen generation is introduced. The Pt QDs@Ni3N‐MoN/Ti catalyst displays outstanding bifunctional seawater catalytic performance, enabling efficient hydrogen production and hydrazine degradation in a flow anion exchange membrane water electrolysis (AEMWE) device. Operating at a low voltage of 1.41 V, it achieves 2 A cm−2 for 300 h, circumventing chlorine corrosion and yielding record‐breaking energy equivalent input (2.68 kWh m−3 H2 at 1 A cm−2), a 47.1% reduction compared to traditional methods. Integration with solar and biomass energy facilitates self‐powered hybrid seawater hydrogen production, highlighting its potential applications. This work facilitates energy‐efficient marine resource conversion to green hydrogen and offers viable insights into industrial hazardous pollutant degradation using metal‐nitride electrocatalysts.

Constructing an oxide-fluoride heterojunction supported on carbon cloth as a highly active and stable catalyst for enhancing overall water-splitting

To realize large-scale production of hydrogen by water electrolysis, the development of inexpensive and high-performance catalysts is urgently needed. Herein, we developed an oxide-fluoride (Co3O4–CoF2) heterojunction catalyst with mooncake shape morphology supported on carbon cloth (CC) used as a bifunctional water electrolysis catalyst in 1 M KOH. The obtained Co3O4–CoF2 heterojunction exhibits a preferable kinetic process and more active sites than its mono components Co3O4 and CoF2, which only needs 46 mV for HER and 169 mV for OER at 10 mA cm−2 comparable to benchmark Pt/C and even super to benchmark IrO2. Meanwhile, it also demonstrates long-term stability, maintaining activity for 100 h for both HER and OER. Importantly, when assembled as a water electrolysis device, only a low cell voltage of 1.45 V is required to achieve the current density of 10 mA cm−2. Meanwhile, it can output continuous and stable current densities of 10, 100, and 10 mA cm−2 approaching 24 h under constant cell voltages of 1.47, 1.69, and 1.47 V, respectively. Therefore, the oxide-fluoride heterojunction catalyst unambiguously is a type of ideal bifunctional water electrolysis catalyst in alkaline media.

Tensile straining of iridium sites in manganese oxides for proton-exchange membrane water electrolysers

Although the acidic oxygen evolution reaction (OER) plays a crucial role in proton-exchange membrane water electrolysis (PEMWE) devices, challenges remain owing to the lack of efficient and acid-stable electrocatalysts. Herein, we present a low-iridium electrocatalyst in which tensile-strained iridium atoms are localized at manganese-oxide surface cation sites (TS-Ir/MnO2) for high and sustainable OER activity. In situ synchrotron characterizations reveal that the TS-Ir/MnO2 can trigger a continuous localized lattice oxygen-mediated (L-LOM) mechanism. In particular, the L-LOM process could substantially boost the adsorption and transformation of H2O molecules over the oxygen vacancies around the tensile-strained Ir sites and prevent further loss of lattice oxygen atoms in the inner MnO2 bulk to optimize the structural integrity of the catalyst. Importantly, the resultant PEMWE device fabricated using TS-Ir/MnO2 delivers a current density of 500 mA cm−2 and operates stably for 200 h.

A low-cost and large-area modular nickel electrode on aramid fabric for efficient solar-driven water electrolysis

We demonstrate a water electrolysis device consisting of two 10 cm2 Ni/aramid flexible electrodes with a Si solar cell with >13% solar-to-hydrogen efficiency over 120 hours stability.

Electrochemical Deposition Processes for Fabrication of Cathodes/Anodes of Alkaline Water Electrolysis Device

Water electrolysis employing anion exchange membranes (AEM) is a promising technique toward the realization of a carbon-neutral society as it facilitates the development of water electrolyzers without noble metals; generally, alkaline electrolytes do not require platinum and iridium oxides for catalysts or titanium for porous transport layers (PTL) and bipolar plates. Although coating techniques have been demonstrated to be effective in forming catalyst layers of cathodes or anodes with lowered resistances [1,2], in this paper, the authors present novel electrochemical methods to produce cathodes/anodes to be used in AEM water electrolysis devices. In the fabrication of cathodes, we use electroless deposition for the direct formation of non-noble metal alloy catalysts on the AEM. This enables ionomer-less attachment of the catalyst layer on the membrane, producing a catalyst that is sufficiently durable under high temperatures. Here, pretreatments for activating the membrane before the deposition are critical. Based on quantum chemical calculations, we found that immersing the membrane in a solution of palladium chloride, prior to its immersion in a reducing agent solution, provides sufficiently stable catalyst nuclei for electroless deposition. For the fabrication of anodes, electrolytic deposition of the catalyst on a PTL is chosen. To retain the porous structure of the PTL, the deposition of a compact film is essential. For this, pulse electrodeposition with an optimized sequence of current density is an attractive technique as it accomplishes metal deposition while retaining the substrate shape. Scanning electron microscopy images in this study proved that the pulse sequence of the current density is beneficial to depositing catalyst alloys with the porous structure of the PTL retained. This is because the pulse technique recovers the depletion of precursor ions for deposition around the electrode surface, which results in preventing the development of diffusion layers. We expect that these processes will make alkaline water electrolysis devices more efficient and cost effective.[1] H. Ito, N. Miyazaki, S. Sugiyama, M. Ishida, Y. Nakamura, S. Iwasaki, Y. Hasegawa, A. Nakano, J. Appl. Electrochem., 48, 305 (2018).[2] H. Ito, N. Kawaguchi, S. Someya, T. Munakata, N. Miyazaki, M. Ishida, A. Nakano, Int. J. Hydrogen Energy, 43, 17030 (2018).AcknowledgementsThis study was financially supported in part by the “Advancement of Hydrogen Technologies and Utilization Project” from the New Energy and Industrial Technology Development Organization (NEDO) of Japan. We would like to express the gratitude to Tokuyama Corporation for the supply of AEM.

Bubble and Dissolved Gas Distribution in Flow through Membraneless Water Electrolysis

Membraneless water electrolysis devices offer an alternative method for hydrogen production without the use of a membrane separator used in traditional alkaline (porous diaphragm) or PEM water electrolysis (polymer electrolyte membrane). This could offer lower capital cost devices (only requiring two electrodes and a cell body) with simple and scalable manufacturing. It could also result in lower operating costs if highly conductive liquid electrolytes are used. Membraneless devices come in a variety of forms including parallel plate, diverging flow through and buoyancy driven devices to name a few. However, the key concept between them is using fluid forces in the bulk electrolyte (controlled by device or porous electrode structure) to remove bubbles from the electrode surfaces and attempt to reduce cross-over of dissolved hydrogen and oxygen, as well as their two-phase flow [1]. Since there is no separator or membrane to restrict transport between the anode and cathode the fluid convection with laminar flows must be used to guide the products to the separate outlets with minimal cross-over and to minimise bubble accumulation on the electrode surfaces. Bubbles on the electrodes increase the activation overpotential by reducing the active electrochemical surface area and decrease the effective conductivity of the flowing electrolyte by inducing tortuous pathways in the electrode gap. In this study, we look at the single-phase and two-phase flow response of flow through membraneless electrolyser by coupling secondary current distribution (which includes the effects of ionic and activation overpotentials) with the volume of fluid method in OpenFOAM. The effects of increasing the length of the device and the electrolyte flow rate on the product cross-over and the dynamic potential of the devices are evaluated to give guidelines for process scale up from 1 to 10 cm. Furthermore, the effect of device porous electrode microstructure on the current density distribution and bubble accumulation is evaluated using custom microstructure reconstruction algorithms built into PMG 1.6 [2]. It was found that there is a balance in flow rate required for uniform flow over the electrodes which depends on the device length and the porous electrode properties. Ordered, graded or unstructured electrodes have different electrochemical performance, and this study highlights some electrode designs that could improve if future manufacturing efforts are increased. Depending on the current density distribution, dissolved gas accumulation and the wettability conditions of the porous electrodes, bubbles may emerge in the electrode gap.Figure 1 - Effect of the hydrogen and oxygen bubble accumulation (yellow) on the ionic current density distribution in a flow through membraneless water electrolyser

Self-assembly of 2D Fe-doped NiTe/NiTe2 heterostructure for boosted oxygen evolution

Highly active and low-cost electrocatalysts composed of non-noble metal elements are essential for acquiring the green hydrogen energy through a large water electrolysis device. In this work, to accelerate the oxygen evolution reaction (OER), the Fe-doped NiTe/NiTe2 heterostructures (termed as Fe-NiTe/NiTe2) were synthesized via a facial one-step process, and further characterized by X-ray diffraction, nitrogen adsorption–desorption test, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. The optimized Fe-NiTe/NiTe2 exhibits a low overpotential of 284 mV at J = 10 mA cm−2 with a small Tafel slope of 49 mV dec−1 and a remarkable durability within a decline of 4.93% after a long-term chronoamperometry test in alkaline electrolyte. The splendid electrocatalytic performance of Fe-NiTe/NiTe2 is ascribed to bimetallic synergy effect and heterostructure of two tellurides after compared with the corresponding catalysts (i.e., NiTe, Fe-NiTe and Fe-NiTe2). In addition, the mechanism reveals that tellurium ions can obviously increases the covalence of Ni-Te bonds and adsorption energy of OH− at the Ni sites, which will significantly promote the efficiency of water oxidation via electrocatalysis. Therefore, this study offers a feasible method for manufacturing the highly active telluride-based electrocatalysts for OER through a one-step solvothermal method.

High-efficiency sustainable energy driven alkaline/seawater electrolysis using a novel hetero-structured non-noble bimetal telluride nanorods

The development of non-noble, economical, and efficient electrocatalysts for water electrolysis will be inevitable for the upcoming green hydrogen economy. In consideration of this, we developed non-noble dual transition metal telluride nanorods through a facile single step hydrothermal method. The optimized CoMnTe2-1 nanorods requires a minimum overpotential of about 120 mV to reach a current density of 10 mA cm−2 in 1.0 M KOH towards the hydrogen evolution reaction (HER). Additionally, we evaluated the theoretical coordination calculations and investigated mechanistic HER pathways using density functional theory calculations. Furthermore, the fabricated water splitting device with CoMnTe2-1 anode displays a cell voltage of 1.60 V and 1.64 V to attain a current density of 10 mA cm−2 in alkaline and alkaline/seawater electrolytes, respectively. As a prototype, we also utilized renewable heat and mechanical energy to drive a self-powered water electrolysis device. This provides a promising path forward in designing an active and efficient bimetal telluride based electrocatalysts for green hydrogen production via alkaline/seawater electrolysis.