Anion Exchange Membrane Water Research Articles

Practical operating flexibility of a bifunctional freestanding membrane for efficient anion exchange membrane water electrolysis across all current ranges

AbstractThis study explores a symmetric configuration approach in anion exchange membrane (AEM) water electrolysis, focusing on overcoming adaptability challenges in dynamic conditions. Here, a rapid and mild synthesis technique for fabricating fibrous membrane‐type catalyst electrodes is developed. Our method leverages the contrasting oxidation states between the sulfur‐doped NiFe(OH)2 shell and the metallic Ni core, as revealed by electron energy loss spectroscopy. Theoretical evaluations confirm that the S–NiFe(OH)2 active sites optimize free energy for alkaline water electrolysis intermediates. This technique bypasses traditional energy‐intensive processes, achieving superior bifunctional activity beyond current benchmarks. The symmetric AEM water electrolyzer demonstrates a current density of 2 A cm−2 at 1.78 V at 60°C in 1 M KOH electrolyte and also sustains ampere‐scale water electrolysis below 2.0 V for 140 h even in ambient conditions. These results highlight the system's operational flexibility and structural stability, marking a significant advancement in AEM water electrolysis technology.

In Situ Electrochemical Rapid Induction of Highly Active γ-NiOOH Species for Industrial Anion Exchange Membrane Water Electrolyzer.

Limited by the strong oxidation environment and sluggish reconstruction process in oxygen evolution reaction (OER), designing rapid self-reconstruction with high activity and stability electrocatalysts is crucial to promoting anion exchange membrane (AEM) water electrolyzer. Herein, trace Fe/S-modified Ni oxyhydroxide (Fe/S-NiOOH/NF) nanowires are constructed via a simple in situ electrochemical oxidation strategy based on precipitation-dissolution equilibrium. In situ characterization techniques reveal that the successful introduction of Fe and S leads to lattice disorder and boosts favorable hydroxyl capture, accelerating the formation of highly active γ-NiOOH. The Density Functional Theory (DFT) calculations have also verified that the incorporation of Fe and S optimizes the electrons redistribution and the d-band center, decreasing the energy barrier of the rate-determining step (*O→*OOH). Benefited from the unique electronic structure and intermediate adsorption, the Fe/S-NiOOH/NF catalyst only requires the overpotential of 345 mV to reach the industrial current density of 1000mAcm-2 for 120 h. Meanwhile, assembled AEM water electrolyzer (Fe/S-NiOOH//Pt/C-60°C) can deliver 1000mAcm-2 at a cell voltage of 2.24V, operating at the average energy efficiency of 71% for 100 h. In summary, this work presents a rapid self-reconstruction strategy for high-performance AEM electrocatalysts for future hydrogen economy.

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.

Stabilization of Lattice Oxygen Evolution Reactions in Oxophilic Ce-Mediated Bi/BiCeO1.8H Electrocatalysts for Efficient Anion Exchange Membrane Water Electrolyzers.

The lattice oxygen mechanism (LOM) offers an efficient reaction pathway for oxygen evolution reactions (OERs) in energy storage and conversion systems. Owing to the involvement of active lattice oxygen enhancing electrochemical activity, addressing the structural and electrochemical stabilities of LOM materials is crucial. Herein, a heterostructure (Bi/BiCeO1.8H) containing abundant under-coordinated oxygen atoms having oxygen nonbonding states is synthesized by a simple electrochemical deposition method. Given the difference in reduction potentials between Bi and Ce, partially reduced Bi nanoparticles and surrounding under-coordinated oxygen atoms are generated in BiCeO1.8H. It is found that the lattice oxygen can be activated as a reactant of the OER when the valence state of Bi increases to Bi5+, leading to increased metal-oxygen covalency and that the oxophilic Ce3+/4+ redox couple can maintain the Bi nanoparticles and surrounding under-coordinated oxygen atoms by preventing over-oxidation of Bi. The anion exchange membrane water electrolyzer with Bi/BiCeO1.8H exhibits a low cell voltage of 1.79 V even at a high practical current density of 1.0 A cm-2. Furthermore, the cell performance remains significantly stable over 100 h with only a 2.2% increase in the initial cell voltage, demonstrating sustainable lattice oxygen redox.

Perovskite for Electrocatalytic Oxygen Evolution at Elevated Temperatures.

The development of advanced electrolysis technologies such as anion exchange membrane water electrolyzer (AEMWE) is central to the vision of a sustainable energy future. Key to the realization of such AEMWE technology lies in the exploration of low-cost and high-efficient catalysts for facilitating the anodic oxygen evolution reaction (OER). Despite tremendous efforts in the fundamental research, most of today's OER works are conducted under room temperature, which deviates significantly with AEMWE's operating temperature (50-80 °C). To bridge this gap, it is highly desirable to obtain insights into the OER catalytic behavior at elevated temperatures. Herein, using the well-known perovskite catalyst Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) as a proof of concept, the effect of temperature on the variation in OER catalytic activity and stability is evaluated. It is found that the BSCF's activity increases with increasing temperature due to enhanced lattice oxygen participation promoting the lattice oxygen-mediated OER process. Further, surface amorphization and cation leaching of BSCF become more pronounced as temperature increases, causing a somewhat attenuated OER stability. These new understandings of the fundamental OER catalysis over perovskite materials at industrial-relevant temperature conditions are expected to have strong implications for the research of OER catalysts to be deployed in practical water electrolyzers.

In Situ Reconstruction to Surface Sulfide Adsorbed Metal Scaffold for Enhanced Electrocatalytic Hydrogen Evolution Activity

AbstractTransition‐metal‐based compounds have been intensively explored as efficient electrocatalysts for hydrogen evolution reaction (HER). Feasible reconstruction to the real active sites, which is yet to be identified, endows the promotion of HER activity. Here, it is reported that the incoming S coordinates and anion vacancies prompt the structural reconstruction of S‐doped Co3O4 on carbon cloth (S‐Co3O4/CC) during HER. A list of in situ studies reveals that the real active sites for HER are the “metallic surface‐adparticles” system embracing metallic Co scaffold and the dilute coverage of S coordinated Coδ+. Reaction mechanism exploration illustrates that interfacial perimeters between the coverage of Co3S4 moieties and metallic Co considerably facilitate the adsorption of H*, improve the kinetics of water dissociation, and consequently promote HER activity. The exemplified sulfide‐mediated topotactic transformation strategy is extended to the preparation of S, Fe codoped Ni(OH)2 (S‐NiFe/CC) as a bifunctional electrocatalyst. The assembled anion exchange membrane water electrolyzer achieves a current density of 1.0 A cm−2 at 1.72 V, showing excellent capability in catalyzing overall water splitting at ampere level. This study, showing a feasible strategy that enables the facile reconstruction to identify active sites, would inspire the development of efficient electrocatalysts for HER and other electrochemical hydrogenation reaction.

Stable Anion Exchange Membrane Bearing Quinuclidinium for High-performance Water Electrolysis.

Anion exchange membranes (AEMs) are core components in anion exchange membrane water electrolyzers (AEM-WEs). However, the stability of functional quaternary ammonium cations, especially under high temperatures and harsh alkaline conditions, seriously affects their performance and durability. Herein, we synthesized a 1-methyl-3,3-diphenylquinuclidinium molecular building unit. Density functional theory (DFT) calculations and accelerated aging analysis indicated that the quinine ring structure was exceedingly stable, and the SN2 degradation mechanism dominated. Through acid-catalyzed Friedel-Crafts polymerization, a series of branched poly(aryl-quinuclidinium) (PAQ-x) AEMs with controllable molecular weight and adjustable ion exchange capacity (IEC) were prepared. The stable quinine structure in PAQ-x was verified and retained in the ex situ alkaline stability. Furthermore, the branched polymer structure reduces the swelling rate and water uptake to achieve a tradeoff between dimensional stability and ionic conductivity, significantly improving the membrane's overall performance. Importantly, PAQ-5 was used in non-noble metal-based AEM-WE, achieving a high current density of 8 A cm-2 at 2 V and excellent stability over 2446 h in a gradient constant current test. Based on the excellent alkaline stability of this diaryl-quinuclidinium group, it can be further considered as a multifunctional building unit to create multi-topological polymers for energy conversion devices used in alkaline environments.

2D Ferromagnetic M3 GeTe2 (M = Ni/Fe) for Boosting Intermediates Adsorption toward Faster Water Oxidation.

In this work, 2D ferromagnetic M3 GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv ) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3 GeTe2v exhibits superior OER activity with only 370mV overpotential to reach the current density of 100mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200mV in alkaline media. Furthermore, a 2D-Ni3 GeTe2v -based anion-exchange membrane (AEM) water electrolysis cell (1 cm2 ) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3V feeding with 0.1 and 1m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3 GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.

Constructing FeNiPt@C Trifunctional Catalyst by High Spin-Induced Water Oxidation Activity for Zn-Air Battery and Anion Exchange Membrane Water Electrolyzer.

Developing cost-efficient trifunctional catalysts capable of facilitating hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) activity is essential for the progression of energy devices. Engineering these catalysts to optimize their active sites and integrate them into a cohesive system presents a significant challenge. This study introduces a nanoflower (NFs)-like carbon-encapsulated FeNiPt nanoalloy catalyst (FeNiPt@C NFs), synthesized by substituting Co2+ ions with high-spin Fe2+ ions in Hofmann-type metal-organic framework, followed by carbonization and pickling processes. The FeNiPt@C NFs catalyst, characterized by its nitrogen-doped carbon-encapsulated metal alloy structure and phase-segregated FeNiPt alloy with slight surface oxidization, exhibits excellent trifunctional catalytic performance. This is evidenced by its activities in HER (-25mV at 10mA cm-2 ), ORR (half-wave potential of 0.93V), and OER (294mV at 10mA cm-2 ), with the enhanced water oxidation activity attributed to the high-spin state of the Fe element. Consequently, the Zn-air battery and anion exchange membrane water electrolyzer assembled by FeNiPt@C NFs catalyst demonstrate remarkable power density (168mW cm-2 ) and industrial-scale current density (698mA cm-2 at 1.85V), respectively. This innovative integration of multifunctional catalytic sites paves the way for the advancement of sustainable energy systems.

Composite anion exchange membranes based on graphene oxide for water electrolyzer applications

Anion Exchange Membrane Water Electrolyzers (AEMWE) hold the promise of combining the advantages of both liquid alkaline and PEM technologies, offering higher purity hydrogen production, improved efficiency, and dynamic behaviour. Nevertheless, AEM systems face notable challenges, particularly in enhancing the ion conductivity and stability of the membrane. The alkaline chemical stability of the AEMs is, in particular, one of the biggest issues, giving the high alkaline solutions used as electrolyte.To overcome those problems, here in this work, the strategy chosen is the simple addition of an inorganic filler in the polymer matrix of the membrane. Various amounts of Graphene Oxide (GO), synthesized using the modified Hummers method, were incorporated into Fumion-based membranes. The resulting AEMs shows improved water uptake, chemical stability, thermal stability and, with the right amount of filler, also enhanced conductivity. In particular, all the composite membranes show diminished weight loss and I.E.C. loss after 170 h in 6 M KOH at 80 °C. The Fumion-GO AEM with 3 %GO (wt%) shows improved conductivity and a remarkable current density higher than 1 A/cm2 at 2 V and 60 °C in the chronoamperometric test.

Valorisation of alkali from tungsten leaching solution using diffusion dialysis and selective electrodialysis for anion-exchange membrane water electrolysis

Currently, tungsten mining procedures discharge a large amount of alkali wastewater, necessitating the development of sustainable approaches to valorise valuable bases for further utilization. In this study, diffusion dialysis (DD) and selective electrodialysis (SED) were utilized to recycle the alkali from a simulated tungsten leaching solution; the recycling base was further subjected to anion-exchange membrane water electrolysis (AEMWE) for H2 production. The results indicate that DD is capable of recycling 0.447 mol/L NaOH base with negligible leakage of WO42−, while the SED process enables the recycling of 1.63–2.01 mol/L NaOH but contains 0.11–0.14 mol/L WO42−. The AEMWE experiment showed that the water electrolyser with SED recycling alkali had a current density of 580.26 mA·cm−2 at 1.8 V, which is much greater than 374.16 mA·cm−2 with DD treatment solution and 352.81 mA·cm−2 without any treatment. The WO42− impurities could adsorb on the surface of the catalyst, which further occupied the catalytic active site of the electrode catalyst and reduced the active specific surface area of the catalyst. This work demonstrated the ability of the SED and DD approaches to recycle alkali for hydrogen production, creating a new pathway for the valorisation of alkali from the tungsten mining industry.

Strong Lewis acid-induced self-healing of loose FeOOH for alkaline oxygen evolution

The fast leaching of the Fe catalytic center and low conductivity of FeOOH have hindered the optimal stability and activity of Fe-based electrocatalysts for oxygen evolution reactions (OER). Here, Zn2+ is introduced into FeOOH with a looser nanosheet structure by regulating electric double layer (EDL) repulsion during electrodeposition. Meanwhile, as strong Lewis acids, Zn2+ in ZnxFeOOH could act as an electron acceptor, accepting electrons from FeOOH. The doping of Zn2+ shortens the bond length of Fe-O and enhances the covalency of Fe-O to improve electron transport rate and stability. The faster catalytic kinetics also been obtained by facilitating O* to form OOH* intermediates. At 100 mA cm−2, Zn0.5FeOOH requires overpotential of only 250 mV and maintains initial activity in 1 M KOH after 120 h. Notably, Zn-induced self-healing is achieved when the leaching and redeposition of Fe reach dynamic equilibrium. In 1 M KOH seawater, Zn0.5FeOOH requires overpotentials of 286 mV to produce current density of 100 mA cm−2. At 2.0 V, Zn0.5FeOOH can achieve 1000 mA cm−2 in anion exchange membrane (AEM) water electrolyzer at room temperature. This work provides an effective Zn-induced strategy for designing efficient and stable OER catalysts for industrial development.

Tensile nanostructured hierarchically porous non-precious transition metal-based electrocatalyst for durable anion exchange membrane-based water electrolysis

Electrochemical water electrolysis is a promising method for sustainable hydrogen production while transiting towards hydrogen economy. Among many, the Anion Exchange Membrane (AEM) based water electrolyzer is an emerging yet potentially affordable technology on maturity for producing large-scale hydrogen accommodating the usage of Non-Platinum Group Metal (non-PGM) based inexpensive electrocatalysts. Herein, we demonstrate the excellent performance of a bifunctional Nickel Copper Phosphide-Nickel sulphide (NCP-NS) electrocatalyst with a unique tensile nanostructure obtained via a facile, controlled ambient galvanic displacement route. An AEM electrolyzer with a larger active area of 10 cm2 stacked with the symmetric NCP-NS electrodes and a membrane demonstrates scalability with a requirement of a mere 1.66 V to reach a current density of 10 mA cm−2. The nickel-copper phosphide boosts the kinetics of charge transfer between the electrode and electrolyte interface, while a unique combination of a few nickel sulphide phases present in the catalyst provides sufficiently appropriate active sites for the overall water electrolysis. For the first time, we report a room temperature performance of ∼ 230 mA cm−2 at 2 V for a non-PGM-based bifunctional electrocatalyst with exceptional durability for over 300 h of operation in an AEM water electrolyser with a retention rate of 95 %-97 % at a current density range of 80–800 mA cm−2.

Investigation of Ionomer and Catalyst (Co3O4, Mn3O4, or MnO2) Interactions Using a Polyethylene Midblock Copolymer in Anion Exchange Water Electrolyzers to Understand Performance and Durability

An anion exchange membrane water electrolyzer (AEMWE) was studied with three electrocatalysts (Co3O4, Mn2O3, MnO2) for the oxygen evolution reactions at 50 °C in 1 M K2CO3(aq). We employ an optimized robust high performance polymer based on a polyethylene mid-block copolymer, poly(vinylbenzyl-N‑methylpiperidinium carbonate)‑b‑polyethylene‑b‑poly(vinylbenzyl-N‑methylpiperidinium carbonate) as the AEM and the anode ionomer. The cathode utilized a high loading of Pt/C, 1 mg cm−2, to minimize contributions to the kinetics. We tested three catalyst loadings (0.5, 2.5, and 4.5 mg cm−2) with a fixed ionomer loading of 0.5 mg cm−2 to assess ionomer-catalyst interactions. The best-performing catalyst loadings were investigated in a 100 h durability test at 750 mA cm−2. The 2.5 mg cm−2 MnO2 catalyst displayed superior performance, with 2.40 ± 0.02 V at 1 A cm−2. In the 100 h durability test, the Mn2O3 catalyst showed a degradation rate of +269 ± 15 μV h−1, whereas Co3O4 and MnO2 showed −800 ± 157 μV h−1, −114 ± 15 μV h−1, respectively with no membrane thinning indicating a gradual improvement. The MnO2 electrode was further investigated in a 500 h test was conducted, revealing a voltage change rate of −21 μV h−1 for 24–375 h. Pre and post-test FTIR mapping revealed evolution of micrometer-sized morphology corresponding to templating by the Ni-foam electrode.

Hierarchical microporous Ni-based electrodes enable “Two Birds with One Stone” in highly efficient and robust anion exchange membrane water electrolysis (AEMWE)

Anion exchange membrane water electrolysis (AEMWE) is currently the most promising technology to produce green hydrogen. However, the lack of cost-effective and scalable methods for fabricating robust and highly active non-noble metal electrodes primarily inhibits its large-scale industrialization. This study unveils an effective strategy for tackling this challenge by creating a novel hierarchical conical-microporous nickel-based electrode, through a synergistic implementation of both rapid and scalable atmospheric plasma spraying (APS) and laser texturing (LT) processes. The resultant NA-LT-CA electrodes exhibits remarkable catalytic performances for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Notably, the AEMWE cell with NA-LT-CA electrodes yields a remarkable enhancement of cell efficiency, toward a reduction in cell voltage of 244 mV at 0.8 A cm−2, compared to the NA-CA electrode (without LT) cell. The notable achievements stem from the improved bubble dynamic contributed by the introduced hierarchical micropores into NA-LT-CA electrodes by the LT process. Moreover, the cell equipped with the NA-LT-CA electrodes demonstrates an outstanding durability, maintaining its performance for 1000 h without visible degradation under 0.8 A cm−2, which can be ascribed to the distinctive “pinning effect” produced by the transition layer during the LT process, adeptly preventing the catalytic layer peeling off even under industrial-scale current densities. Notably, introducing the LT process delivers a dual benefit, akin to achieving “Two Birds with One Stone.”. This work supports the effectiveness of combining APS and LT processes as a potent strategy for fabricating high-efficiency and enduring electrodes, thus advancing AEMWE for practical industrial applications.

Interface-Engineered NiFe/Ni-S Nanoparticles for Reliable Alkaline Oxygen Production at Industrial Current: A Sulfur Source Confinement Strategy.

Using powder-based ink appears to be the most suitable candidate for commercializing the membrane electrode assembly (MEA), while research on the powder-based NPM catalyst for anion exchange membrane water electrolyzer (AEMWE) is currently insufficient, especially at high current density. Herein, a sulfur source (NiFe Layered double hydroxide adsorbed ) confinement strategy is developed to integrate Ni3 S2 onto the surface of amorphous/crystalline NiFe alloy nanoparticles (denoted NiFe/Ni-S), achieving advanced control over the sulfidation process for the formation of metal sulfides. The constructed interface under the sulfur source confinement strategy generates abundant active sites that increase electron transport at the electrode-electrolyte interface and improve ability over an extended period at a high current density. Consequently, the constructed NiFe/Ni-S delivers an ultra-low overpotential of 239mV at 10mA cm-2 and 0.66mA under an overpotential of 300mV. The AEMWE with NiFe/Ni-S anode exhibits a cell voltage of 1.664V @ 0.5 A cm-2 and a 400h stability at 1.0Acm-2 .

ETFE-grafting ionomers for anion exchange membrane water electrolyzers with a current density of 11.2 A cm−2

In the quest for efficient and sustainable hydrogen production, anion exchange membrane (AEM) water electrolyzers (AEMWEs) have gained significant attention. Development of AEMs has accelerated in the past few decades while the significance of the ionomer on AEMWE performance and durability is always unrecognized. In this study, we proposed a class of electrochemically durable ionomers by introducing the piperidinium group onto the ethylene tetrafluoroethylene (ETFE) backbone using a radiation grafting technology. To avoid disruption of the conformation of the piperidinium group during the functionalization process, we grafted the piperidinium group onto the polymer backbone at the gamma position of the N-piperidinium group using trifluoromethanesulfonic acid as a catalyst. The prepared ETFE-g-poly(styryl propyl piperidinium) ionomers exhibited outstanding electrochemical properties and enhanced alkaline stability. Most notably, the corresponding AEMWEs demonstrated an impressive current density of 11.2 A cm−2 at 2.0 V under 80 °C in 1 M KOH solution. Furthermore, they were continuously operated at a current density of 0.5 A cm−2 for over 300 h with a low voltage decay rate of 0.12 mV h−1. This study offers valuable insights into the development of robust solid-state ionomers through radiation grafting, paving the way for high-performance AEMWEs.

Sulfate anchored on the defective NiO by ion irradiation realizes enhanced oxygen evolution reaction

NiO has attracted wide attention in the past decade as a cost-effective electrochemical catalyst for OER. However, its relatively poor performance and conductivity limit its commercial applications. Here, we highlight a unique ion irradiation method to enhance the catalytic activity of NiO. Benefiting from sulfate anchoring and the introduction of oxygen vacancies by He+ ion irradiation, the optimal catalyst (ir-S-NiO) exhibits an outstanding OER performance with a low overpotential of 269 mV at 10 mA cm−2. Moreover, the fabricated Anion exchange membrane water electrolyzer (AEMWE) constructed by the ir-S-NiO is demonstrated to need a cell voltage of 1.72 V to reach a current density of 0.1 A cm−2 and shows remarkably long-term stability for 200 h without obvious attenuation at the current density of 0.5 A cm−2. This work provides a new method for the development of high-performance and stable OER electrocatalysts.

Facilitating alkaline hydrogen evolution reaction on the hetero-interfaced Ru/RuO2 through Pt single atoms doping

Exploring an active and cost-effective electrocatalyst alternative to carbon-supported platinum nanoparticles for alkaline hydrogen evolution reaction (HER) have remained elusive to date. Here, we report a catalyst based on platinum single atoms (SAs) doped into the hetero-interfaced Ru/RuO2 support (referred to as Pt-Ru/RuO2), which features a low HER overpotential, an excellent stability and a distinctly enhanced cost-based activity compared to commercial Pt/C and Ru/C in 1 M KOH. Advanced physico-chemical characterizations disclose that the sluggish water dissociation is accelerated by RuO2 while Pt SAs and the metallic Ru facilitate the subsequent H* combination. Theoretical calculations correlate with the experimental findings. Furthermore, Pt-Ru/RuO2 only requires 1.90 V to reach 1 A cm−2 and delivers a high price activity in the anion exchange membrane water electrolyzer, outperforming the benchmark Pt/C. This research offers a feasible guidance for developing the noble metal-based catalysts with high performance and low cost toward practical H2 production.

Alleviating OH Blockage on the Catalyst Surface by the Puncture Effect of Single-Atom Sites to Boost Alkaline Water Electrolysis.

Nonprecious transition metal catalysts have emerged as the preferred choice for industrial alkaline water electrolysis due to their cost-effectiveness. However, their overstrong binding energy to adsorbed OH often results in the blockage of active sites, particularly in the cathodic hydrogen evolution reaction. Herein, we found that single-atom sites exhibit a puncture effect to effectively alleviate OH blockades, thereby significantly enhancing the alkaline hydrogen evolution reaction (HER) performance. Typically, after anchoring single Ru atoms onto tungsten carbides, the overpotential at 10 mA·cm-2 is reduced by more than 130 mV (159 vs 21 mV). Also, the mass activity is increased 16-fold over commercial Pt/C (MA100 = 17.3 A·mgRu-1 vs 1.1 A·mgPt-1, Pt/C). More importantly, such electrocatalyst-based alkaline anion-exchange membrane water electrolyzers can exhibit an ultralow potential (1.79 Vcell) and high stability at an industrial current density of 1.0 A·cm-2. Density functional theory (DFT) calculations reveal that the isolated Ru sites could weaken the surrounding local OH binding energy, thus puncturing OH blockage and constructing bifunctional interfaces between Ru atoms and the support to accelerate water dissociation. Our findings exhibit generality to other transition metal catalysts (such as Mo) and contribute to the advancement of industrial-scale alkaline water electrolysis.