Non-precious Electrocatalysts Research Articles

Novel and superhydrophilic bifunctional NiCuMn@TiN nanosheets supported on iron foam for high-performance supercapacitors and water oxidation

Synthesizing low-cost and highly efficient bifunctional electrocatalysts for hybrid supercapacitors and oxygen evolution reaction (OER) is critically essential for the progress of energy storage and conversion devices. Therefore, a novel, inexpensive and superhydrophilic bifunctional NiCuMn@TiN nanosheet supported on iron foam (NiCuMn@TiN/IF) is successfully designed and fabricated via spent cupronickel (SCN) as Ni and Cu precursor by a facile one-step electrosynthesis routine. With adding nano titanium nitride (TiN), the obtained NiCuMn@TiN/IF composite electrode not only possesses a large superhydrophilic surface that enhances ion/electron transfer efficiency and provides numerous activity sites for the electrochemical reaction but also achieves efficient recovery of metal resources using the secondary resource SCN as soluble anode further reduces the cost of electrode preparation. And since the synergistic effect of large specific surface area and superhydrophilicity, the NiCuMn@TiN/IF delivers a high specific capacity of 22.5 F cm−2 at 10 mA cm−2 in 3 M KOH and also illustrates superior OER activity with an extremely low overpotential (286 mV) and remarkable durability at a high current density of 100 mA cm−2 in 1 M KOH. This research provides a solid foundation for the large-scale preparation of low-cost and high-performance non-precious metal bifunctional electrocatalysts for the commercial development of electrochemical supercapacitors and electrochemical water-to-hydrogen conversion technology.

Ni/Fe2O3 Mott-Schottky heterointerface engineering and phosphate doping synergistically refining d-band center for efficient oxygen evolution reaction

Developing highly effective non-precious metal-based electrocatalysts is pivotal to overcome unfavorable slow kinetics of oxygen evolution reaction (OER) and large-scale application limitations of noble metals. Herein, a dual-modulation strategy of anion incorporation and Mott-Schottky heterointerface engineering was adopted to synthesize phosphate-doped Ni/Fe2O3 heterostructure (Pi-Ni/Fe2O3). Experimental combined theoretical calculations evident that the strong coupling between Ni and Fe2O3 leads to the redistributed electron and charge at the heterointerface and the reduction of bandgap, and adjusts electronic density of state around active centers into the bargain. Moreover, phosphate incorporation can reduce the probability of anti-bond filling, and serve as proton acceptors to form hydrogen bonds for stabilizing *OOH intermediates. Heterostructure formation and phosphate doping induce the upshift of d-band center of Pi-Ni/Fe2O3, giving lower energy barrier toward OER compared with Fe2O3 and Ni. Consequently, the above merits endow Pi-Ni/Fe2O3 with outstanding OER performance to deliver 10 mA cm−2 at an overpotential of 263 mV, as well as superior electrocatalytic performance for overall water splitting. This study not only reveals the synergistic effect of Schottky heterogeneous interface and phosphate doping, but also sheds light on advancing high-efficiency catalysts from the perspective of proton receptor modification and interface engineering.

Recent Advances and Synergistic Effects of Non-Precious Carbon-Based Nanomaterials as ORR Electrocatalysts: A Review

The use of platinum-free (Pt) cathode electrocatalysts for oxygen reduction reactions (ORRs) has been significantly studied over the past decade, improving slow reaction mechanisms. For many significant energy conversion and storage technologies, including fuel cells and metal–air batteries, the ORR is a crucial process. These have motivated the development of highly active and long-lasting platinum-free electrocatalysts, which cost less than proton exchange membrane fuel cells (PEMFCs). Researchers have identified a novel, non-precious carbon-based electrocatalyst material as the most effective substitute for platinum (Pt) electrocatalysts. Rich sources, outstanding electrical conductivity, adaptable molecular structures, and environmental compatibility are just a few of its benefits. Additionally, the increased surface area and the simplicity of regulating its structure can significantly improve the electrocatalyst’s reactive sites and mass transport. Other benefits include the use of heteroatoms and single or multiple metal atoms, which are capable of acting as extremely effective ORR electrocatalysts. The rapid innovations in non-precious carbon-based nanomaterials in the ORR electrocatalyst field are the main topics of this review. As a result, this review provides an overview of the basic ORR reaction and the mechanism of the active sites in non-precious carbon-based electrocatalysts. Further analysis of the development, performance, and evaluation of these systems is provided in more detail. Furthermore, the significance of doping is highlighted and discussed, which shows how researchers can enhance the properties of electrocatalysts. Finally, this review discusses the existing challenges and expectations for the development of highly efficient and inexpensive electrocatalysts that are linked to crucial technologies in this expanding field.

Amorphous-crystalline heterostructures enable energy-level matching of cobalt sulfide/nickel iron layered double hydroxide for efficient oxygen evolution reaction

Interface engineering of heterostructures has emerged as a promising approach to enhance the catalytic activity of nonprecious electrocatalysts. Herein, a novel amorphous cobalt sulfide-crystalline nickel iron layered double hydroxide (a-CoS@NiFe-LDH) hybrid material is presented for application as an electrocatalyst for oxygen evolution reaction (OER). Benefitting from the well-matched energy level structures, the a-CoS@NiFe-LDH catalyst delivers a low overpotential of 221 ± 14 mV at an OER current density of 20 mA cm−2 and a small Tafel slope of 83.1 mV dec-1, showing good OER properties. First-principle computations reveal that the electronic interaction between amorphous cobalt sulfide (a-CoS) and crystalline nickel iron layered double hydroxide (NiFe-LDH) components within a-CoS@NiFe-LDH promotes the adsorbate evolution mechanism and reduces the adsorption energies for oxygen intermediates, thereby enhancing the activity and stability for OER. This work opens up a new avenue to enhance the OER catalytic efficiency via the construction of amorphous-crystalline heterostructures.

Facile synthesis of the multidimensional oxygen redox electrocatalysts by anion-mediated self-template one-step in situ assembly

The exploration of a non-precious metal bifunctional electrocatalyst with novel structures for the efficient oxygen reduction reaction (ORR) and oxygen evolution reactions (OER) remains a great challenge. Multidimensional assembled nanostructures with nitrogen-doped carbon matrix inlaid with transition-metal (M-N-C) can be used as efficient electrocatalysts due to its large surface area and highly revealed active sites. Herein, we report an anion-mediated self-template one-step in situ transformation into multidimensional hierarchical nano-assembled M-N-C catalysts, which is assembled from 0D cobalt nanoparticles terminally inlaid in 1D carbon nanotubes growing on a honeycomb-like ultrathin 3D carbon network (denoted as Co@N-CNTs/CS). By further synthetic process characterization, the nitrate-mediated structural evolution during rising thermal stages is disclosed. Thanks to the fully exposed surfaces and highly accessible active sites in the unique multidimensional structure, our developed catalyst exhibits a large surface area and enhanced performance in bifunctional oxygen redox in alkaline media, which further endows potentials in rechargeable Zn-air batteries, surpassing the typical benchmark catalysts Pt/C + Ir/C. Our study affords a fresh path to facile fabrication of M-N-C electrocatalysts.

Synthesis of defect-engineered molybdenum sulfides on reduced graphene oxide for enhanced hydrogen evolution reaction kinetics

Amorphous molybdenum sulfide (a-MoS3) is a promising non-precious electrocatalyst for hydrogen evolution reaction owing to the abundant defective active sites. Here in, we show a rapid microwave-assisted synthesis method to produce a-MoS3 catalysts on reduced graphene oxide (rGO) substrates. The a-MoS3 reported in this study comprise of two possible 1D chain-like structures, i.e., with molybdenum (IV) in Weber's model and molybdenum (V) in Hibble's model, unlike the polymeric cluster type a-MoS3 structures reported in literature. Thermal annealing of the microwave-prepared a-MoS3 produced a family of defect-engineered MoSx/rGO hybrids, from a-MoS3 to crystalline MoS2, which showed tunable HER activities. XPS analysis provided in-depth understanding of the compositional changes in MoSx/rGO with thermal annealing. The a-MoS3/rGO 250 (annealed at 250 °C) exhibited the highest HER catalytic activity among all the MoSx/rGO hybrids, with an overpotential of 208 mV at 10 mA/cm2, a low Tafel slope of 52 mV/decade, a high double layer capacitance of 3.7 mF/cm2 and a high TOF value of 0.43 H2/s per site at the HER overpotential of 208 mV. The excellent HER activity is attributed to both MoV and sulfur active sites. This study provides a controllable, scalable and rapid synthesis method to produce 1D chain-like a-MoS3 structures for HER electrocatalysis.

Water hyacinth root derived hybrid metal oxides/nitrogen doped porous carbon as an efficient non-precious metal oxygen reduction reaction electrocatalyst in alkaline media

A biomass derived hybrid metal oxides/nitrogen doped porous carbon (NC) electrocatalyst is fabricated by direct pyrolysis of the water hyacinth root (WHR) mixed ZnCl2 raw materials at 600 °C (WHR600), 700 °C (WHR700) and 800 °C (WHR800) under autogenic pressure conditions. XRD analysis presents a novel Zn(Al1.8Fe0.2)O4 compound combined with hematite quart and muscovite phases for WHR700 and WHR800 samples. In addition, the WHR700 sample accounts for the maximum pyridinic N content incorporated into carbon framework (NC). Electrochemically, the WHR700 catalyst displays the highest oxygen reduction reaction (ORR) performance in alkaline media. The high ORR performance for WHR700 catalyst is significantly a result of the presence of the Zn(Al1.8Fe0.2)O4 phase and the pyridinic N species. Furthermore, an accelerate durability test for WHR700 sample over 5000 cycles exhibits only 8 mV half-wave potential reduction. The WHR700 catalyst is also extremely stable to the methanol poisoning during ORR operation.

Defect engineering induces Mo-regulated Co9Se8/FeNiSe heterostructures with selenium vacancy for enhanced electrocatalytic overall water splitting in alkaline

The pursuit of cost-effective catalysts for electrocatalytic overall water splitting continues to present a significant challenge in the field. A molybdenum (Mo)-regulated Co9Se8/FeNiSe self-supporting electrode material with rich vacancy defects has been prepared by hydrothermal reaction. Doping of Mo atoms not only can form rich selenium vacancy defects to enrich the inherent activity of the catalyst, but also expose more active sites. The intrinsic electronic architecture of the interface catalysis is regulated and optimized through the introduction of heteroatom Mo, resulting in the exceptional catalytic activities of the Mo-Co9Se8/FeNiSe heterostructure. Additionally, the Faraday efficiency of hydrogen (H2) and oxygen (O2) production approaches 100 %. The voltage required for the water-splitting system is only 1.58 V (10 mA cm−2), and 100 h stability test at 100 mA cm−2 demonstrates no decay. This work presents a new perspective for the reasonable design and synthesis of non-precious metal selenide-based bifunctional electrocatalysts.

Hydrothermal synthesis of ZnO@MoTe2 nanocomposite as excellent electrocatalyst for hydrogen evolution reaction (HER)

The comprehension of novel fundamental inquiries about the design of electrocatalysts is of paramount importance in enhancing the availability of renewable energy resources and advancing the progress of exceptionally durable and effective nonprecious electrocatalysts for the process of water splitting. Enhancing the capacity of renewable energy storage systems through the usage of nonprecious nanocomposites for efficient H2O splitting holds the potential to foster a more sustainable and environmentally conscious society, hence mitigating the impact of global warming. The nanocomposite exhibits proficient catalytic kinetics for the HER process owing to the enhanced accessibility of MoTe2′s most active zones. The physical property of the nanocomposite was established through in-process characterization using different analytical techniques. In a basic environment, the ZnO@MoTe2 combination exhibited a significant value for the generation of hydrogen using electrocatalysts based on ZnO@MoTe2, which was a 34 mV dec-1 Tafel slope. The nanocomposite exhibited a higher turn-over frequency rate (TOF) of 2.4 s−1 than pure materials. The ZnO@MoTe2 nanocomposite displays a higher surface area of 1125 cm2 and a low Rct value of 93 Ω. The electrocatalyst exhibits exceptional stability and durability. During 50 h in an alkaline environment, the application of chronopotentiometry reveals no substantial decrease in potential. The utilization of nanocomposite based electrocatalysts has been shown to provide efficient quick charge kinetics, a noteworthy observation. The results of this study offer a novel, reliable and effective electrocatalyst that has potential applications in the advancement of electrocatalytic devices for hydrogen gas (H2) production. These devices can be developed employing cost-effective technologies and naturally occurring materials widely available worldwide.

Amorphous quaternary alloy nanoplates for efficient catalysis of hydrogen evolution reaction

Developing a highly efficient non-precious transition metal-based electrocatalyst via a facile approach toward the hydrogen evolution reaction (HER) is critical for large-scale hydrogen production but still remains challenging. Herein, a cost-effective electrochemical deposition strategy is rationally proposed to construct amorphous quaternary FeCoNiCu alloy nanosheets supported on nickel foam (NF) towards this challenge. Benefiting from the synergistic effect of multi-metal atoms interaction and the high exposure of active sites caused by abundant open voids, the as-synthesized FeCoNiCu/NF electrode exhibits high catalytic activity and robustness toward HER in alkaline solution, requiring an overpotential of only 35 mV to reach a current density of 10 mA cm–2. This study may pave a new avenue to design advanced electrocatalyst for energy conversion.

Design of CoSbyOx/Ti electrocatalyst via facile thermal decomposition method for durable and high temperature chlorine evolution reaction in acidic media

Developing stable and cost-effective electrodes for the anode compartment of chlor-alkali process to drive the chlorine evolution reaction (CER) has remained as a challenge. This study introduces CoSbyOx/Ti as a durable and non-precious anode electrocatalyst synthesized via facile and scalable thermal decomposition method. This novel electrode permanently conducts CER for 240 h under 100 mA.cm−2 at 70 °C in 4 M NaCl (pH=2) with an overpotential of only 498 mV and a high selectivity of 92.2 % toward CER. From XRD results, crystalline CoSb2O6 forms above 600 °C and acts as active and stable phase during CER. From XPS analysis, a combination of Co3+ and Co2+ forms on the surface of the electrode; the content of Co3+ species increases after CER which can reduce structural defects and hence improve the stability of the structure. We further shed more light on the degradation mechanism of this type of electrodes by performing additional 240 h durability test under accelerated condition of 1000 mA.cm−2. Observations indicate a failure mechanism that is probably a combination of deactivation of the electrode and catalyst detachment in accelerated conditions.

Surface oxidation of commercial activated carbon with enriching carboxyl groups for high-yield electrocatalytic H2O2 production

Two-electron oxygen reduction reaction (2e− ORR) for H2O2 production is regarded as a more ecologically friendly substitute to the anthraquinone method. However, the search of selective and cheap catalysts is still challenging. Herein, we developed a neutral-selective and efficient nonprecious electrocatalyst that was prepared from a commercial activated carbon (AC) by simply microwave-assisted ash impurity elimination and hydrogen peroxide oxidation for surface functional sites optimization. The oxygen configuration can be tuned with enriching carboxyl group up to 6.65 at.% by the dosage of hydrogen peroxide (mass ratio of H2O2/C = ∼0–8.3). Chemical titration experiments identified the carbonyl groups as the most potential active sites, with selectivity boosted by the additional carboxyl groups. The microwave-assisted moderate-oxidized activated carbon (MW-AC5.0) demonstrated optimal 2e− ORR activity and selectivity in neutral electrolyte (0.1 M K2SO4), with H2O2 selectivity reaching ∼75%–97%, a maximum H2O2 production rate (1.90 mol·gcatal −1·h−1@0.1 V) and satisfying faradaic efficiency (∼85%) in gas-diffusion-electrode. When coupled with Fenton reaction, it can degrade a model organic pollutant (methylene blue [MB], 50 ppm) to colorless in a short time of 20 min, indicating the potential applications in the environmental remediation.

Ambient plasma treated iron-doped flower-shaped molybdenum disulfide for efficient electrocatalyst

Developing a nonprecious, bifunctional, and efficient electrocatalyst for water splitting is crucial for future renewable fuel systems, yet it remains a significant challenge. In this study, we tackle the challenge by activating molybdenum disulfide (MoS2) through iron doping and ambient plasma treatment. We synthesize 1 T phases flower-shaped plasma treated iron-doped MoS2 (P-Fe-MoS2), since 1 T-MoS2 has higher electrocatalytic activity and larger electrical conductivity, compared to 2H-MoS2. P-Fe-MoS2 shows 79 % of 1 T phase, resulting in enhanced catalytic performance, such as low overpotential of −122 mV with Tafel slope of 47 mV/dec at −10 mA/cm2 for hydrogen evolution reaction and low overpotential of 206 mV with Tafel slope of 69 mV/dec at the current density of + 10 mA/cm2 for oxygen evolution reaction. This study shows the development of 1 T phase on the synthesized Fe doped 2H-MoS2 by the ambient plasma method, which could be used widely for modifications of other energy materials.

Bionic Fe-N-C catalyst with abundant exposed Fe-Nx sites and enhanced mass transfer properties for efficient oxygen reduction

Transition metal and nitrogen co-doped carbon electrocatalysts are promising candidates to replace the precious metal platinum (Pt) in oxygen reduction reactions (ORR). Unfortunately, the electrochemical performance of existing electrocatalysts is restricted due to limited accessibility of active sites. Inspired by jellyfish tentacles, we design an efficient ORR micro-reactor called Fe-Nx/HC@NWs. It features abundant exposed Fe-Nx active sites dispersed on nitrogen-doped cubic carbon cages, which have a hierarchically porous and hairy structure. The accessible, atomically dispersed Fe-Nx sites and the elaborate substrate architecture synergize to provide the catalyst withremarkable ORR catalytic activity, extraordinary long-term stability, and favorable methanol tolerance in an alkaline electrolyte; overall, its performance is comparable to that of commercial carbon-supported Pt. Our synthesis is facile and controllable, paving a new avenue toward advanced non-precious metal-based electrocatalysts for energy storage and conversion.

Unraveling the Cooperative Activity of Hydrophilicity, Conductivity, and Interfacial Active Sites in Alginate‐CNT‐Cuo Self‐Standing Electrodes with Benchmark‐Close Activity for Alkaline Water Splitting

AbstractDesigning electrocatalysts that excel in hydrogen and oxygen electrochemistry is crucial for sustainable hydrogen generation through electrochemical water splitting. This study presents a novel tricomponent catalyst composed of an alginate hydrogel (AL) infused with single‐walled carbon nanotubes (CNTs) and copper oxide (CuO) nanoparticles. The catalyst exhibits benchmark‐close bifunctional activity toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions. The aerophobic nature of the AL‐gel facilitates superior bubble release from the electrode, while the inclusion of CNTs mitigates charge transfer resistance. Moreover, heterojunctions of CuO and CNTs create unique interfacial active sites, culminating in high electrocatalytic water‐splitting activity. The structural rigidity of the composite permits its use as self‐standing electrodes (SSE) without using substrates or binders, enabling a direct evaluation of its activity. The composite electrode demonstrates exceptional electrocatalytic HER activity in an alkaline solution, with onset potentials of 93 mV and moderate OER activity with an onset of 155 mV. Moreover, a water electrolysis cell featuring the bifunctional SSE exhibits an open circuit voltage of 1.85 V at 100 mA.cm−2, and only 8% efficiency loss after 100 h marking this a significant stride in developing self‐standing nonprecious electrocatalysts with impressive catalytic performance.

Modulating electronic structure of Ni/carbon spherical nano-superstructures through transition metal-doping as highly efficient catalysts for hydrogen evolution reaction

The development of low-cost, high-performance electrocatalysts for hydrogen precipitation reactions is the key to solving the energy crisis. Metal organic framework (MOFs) with metal centers and organic ligands are one of the ideal materials for the preparation of non-precious metal carbon-based HER electrocatalysts. In this work, a series of transition metal-doped nano-superstructures carbon-based materials NiMC (M = Fe, Co, Cu) were designed and prepared by introducing different transition metal atoms using Ni-MOF as precursors. And the effect of transition metal doping on the electrocatalytic hydrogen precipitation performance of Ni-MOF has been systematically investigated. Nitrogen adsorption tests have shown that the NiFeC catalyst has the highest specific surface area. The overpotential was only 69 mV at a current density of 10 mA cm−2 in an alkaline electrolyte and exhibited excellent stability. Density functional theory (DFT) calculations show that the electronic interactions between Fe and Ni are tuned after Fe atom doping, which optimizes the hydrogen adsorption energy leading to the excellent HER catalytic performance of NiFeC.

Adding Fe/dicyandiamide to Co-MOF to greatly improve its ORR/OER bifunctional electrocatalytic activity

Exploring efficient non-precious metal oxygen electrocatalysts for oxygen reduction/evolution reactions (ORR/OER) is of great importance in electrochemical energy conversion devices like metal-air battery. Among them, carbon-based composites derived from metal-organic framework (MOF) exhibit excellent catalytic performance in ORR/OER. In this paper, Co-MOF-67 was firstly prepared, and then mixed with FeCl3·6 H2O and dicyandiamide, followed by a one-step pyrolysis to obtain bamboo-like nitrogen-doped carbon nanotubes. For the samples, Fe and Co nanoparticles were encapsulated in the front end of the carbon nanotubes and the presence of new (n)-diamond carbon was unexpectedly found. The obtained catalyst (FeCo@CNTs-60) has an onset potential of 1.04 V for ORR in alkaline solution, which is close to the commercial Pt/C (40 wt% Pt) of 1.05 V. The onset potential of 1.02 V in quasi-neutral solution exceeds that of Pt/C of 0.99 V. In addition, FeCo@CNTs-60 exhibited a low potential difference of 0.81 V between OER and ORR potentials. The alkaline zinc-air batteries, fabricated with the sample as the electrocatalyst of air electrode, exhibit higher peak power density and stability than Pt/C, while the rechargeable batteries present superior cycling discharge/charge stability at 5 mA·cm−2 and 10 mA·cm−2. In particular, the battery with FeCo@CNTs-60 was conducted for continuous over 1300 h of ultra long-term cycle charging / discharging test at a current density of 5 mA·cm−2, and it reveals excellent stability with high voltage efficiency and also presents superior cycle charging / discharging stability after replacing the Zn plates and electrolyte.

Cobalt-doped WSe2@conducting polymer nanostructures as bifunctional electrocatalysts for overall water splitting

Designing of high-performance, low-cost, and nonprecious metal-based bifunctional electrocatalysts is highly significant for the development of water splitting process and expanding the practical application of green hydrogen production. Transition metal dichalcogenides (TMDs) with intrinsic physical and chemical properties have been considered potential catalytic materials for electrode fabrication. However, it has remained challenging to develop TMD catalysts that have bifunctional properties for overall water splitting. Herein, WSe2, as a typical representative of TMDs, was utilized to design electrocatalysts using polypyrrole (PPy) or polyaniline (PANI) as a conducting polymer (CP) and cobalt doping. A facile hydrothermal preparation of WSe2 in the presence of CP enabled the construction of cobalt-doped WSe2@CP electrocatalysts. Morphological analysis indicated that the CP played an important role as a conductive template to enhance the distribution of WSe2 nanosheets, leading to higher surface area. In addition, cobalt doping led to the formation of defect structures and boosted the electrocatalytic activities of the catalysts for oxygen evolution reaction (OER). Owing to the increased electrochemical surface area and defect structures, the cobalt-doped WSe2@CP nanostructures exhibited enhanced electrochemical properties for hydrogen evolution reaction (HER) and OER in an alkaline medium. The cobalt-doped WSe2@PANI modified glassy carbon electrode (GCE) exhibited overpotentials down to 308 and 360 mV at a current density of 10 mA cm−2 for the HER and OER, respectively. Furthermore, the cobalt-doped WSe2@CP electrocatalysts demonstrated long-term stability and continuous cycling. More importantly, the Co–WSe2@PANI electrolyzer required cell voltage of 1.87 V at a current density of 10 mA cm−2 for overall water splitting process. This work provides new findings for designing efficient bifunctional electrocatalysts utilizing TMD materials and conducting polymers.

Hierarchical Heterogeneous NiFe Layered Double Hydroxides for Efficient Solar-Powered Water Oxidation.

Highly active, stable, and low-cost oxygen evolution reaction (OER) electrocatalysts are urgently needed for the realization of large-scale industrial hydrogen production via water electrolysis. Layered double hydroxides (LDHs) stand out as one of the most promising nonprecious electrocatalysts worth pursuing. Here, a hierarchical heterogeneous Ni2+Fe3+@Ni2+Fe2+ LDH was successfully synthesized via a sequential electrodeposition technique using separate electrolytes containing iron precursors with different valence states (Fe2+, Fe3+). The underlying highly crystalline Ni2+Fe2+ LDH nanosheet array provides a large surface for the catalytically more active Ni2+Fe3+ LDH overlayer with low crystallinity. The resulting Ni2+Fe3+@Ni2+Fe2+ LDH demonstrates excellent OER activity with overpotentials of 218 and 265 mV to reach current densities of 10 and 100 mA cm-2, respectively, as well as good long-term stability for 30 h even at a high current density of 500 mA cm-2. In an overall water splitting, an electrolyzer using an electrocatalyst of Sn4P3/CoP2 as a cathode requires only a cell voltage of 1.55 V at 10 mA cm-2. Furthermore, the solar-powered overall water splitting system consisting of our electrolyzer and a perovskite/Si tandem solar cell exhibits a high solar-to-hydrogen conversion efficiency of 15.3%.

Development of High Durable Pore-Filling Anion Exchange Membranes for Water Electrolysis Application

Water electrolyzer is a device that converts renewable electrical energy into environmentally friendly chemical energy, hydrogen. Water electrolysis is mainly categorized into proton exchange membrane water electrolysis (PEMWE) and anion exchange membrane water electrolysis (AEMWE). Non-precious electrocatalysts and hydrocarbon-based polymeric membranes are used for two different systems. It is advantageous for AEMWE in terms of cost. However, low current density and chemical stability for current anion exchange membrane technology (AEM) restricts early market penetration. Thus, thedevelopment of low resistance and high durable AEMs is of importance. In this study, superior ion conductivity and high durable pore-filling AEMs were developed for AEMWE. Pore-filling AMEs with different contents of crosslinking monomers were prepared by the monomers using chemically stable anion exchangeable functional groups in a porous polyethylene(PE) substrate. Properties of the AEMs were characterized through areal resistance, ionic conductivity, ion exchange capacity, water uptake, swelling ratio, mechanical strength and hydrogen crossover. In addition, AEMWE performance and durability tests were also conducted. Acknowledgments This research was supported in part by Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ016253), Rural Development Administration, Republic of Korea and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.