Anode Catalyst Research Articles

Methanol‐Facilitated Surface Reconstruction Catalysts for Near 200% Faradaic Efficiency in a Coupled System

AbstractThe coupling of the carbon dioxide reduction reaction (CO2RR) and methanol oxidation reaction (MOR) holds great promise for the energy‐efficient production of HCOO−. However, anode catalysts' limited selectivity (<80%) and stability (<15 h) have impeded electron utilization and HCOO− production rates. To overcome it, copper‐copper(I) oxide‐copper(II) oxide nanowires (Cu─CuO─Cu2O NWs) catalysts have been developed, which exhibit exceptional performance in promoting the MOR with a faradic efficiency of nearly 100% at commercially viable current densities, and long stability over 100 h at 100 mA cm−2. Interestingly, the unique structure of the catalysts, when exposed to methanol, facilitates a transition from Cu/CuO to Cu2O. This phenomenon promotes the MOR while inhibiting the competitive oxygen evolution reaction (OER). By coupling the anodic reaction with cathodic CO2 reduction, the system demonstrates exceptional performance in HCOO− production, achieving an overall faradic efficiency of nearly 200% at 100 mA cm−2 with a low cell voltage of 2.382 V. Techno‐economic analysis indicates that the production costs of HCOOH are ≈US$0.37 and 0.35 kg−1 at 100 and 150 mA cm−2, respectively, significantly lower than those associated with traditional electrochemical methods.

Synergistic gradient distribution of IrO2/TiNX ratio and ionomer content reduces the internal voltage loss of the anode catalytic layer in PEM water electrolysis

The design of the anode catalyst layer (ACL) is crucial to the performance and stability of PEM electrolyzers. In this work, the ACL was designed into three sublayers, each different in ionomer content and IrO2/TiNX ratio. The high ionomer content of the subset layer will reduce the utilization of the active sites of the catalytic layer, but based on the improvement of the kinetic performance and proton conductivity near the membrane interface, increased mass transport can be achieved. A higher Ir loading near the gas diffusion layer (PTL) and less Ir loading near the membrane interface can improve cell performance, especially at high current densities. The abundance of bubbles produced by oxygen evolution reduces the three-phase reaction boundary, which results in a low utilization rate of the catalyst close to the membrane. In contrast, more Ir in the catalytic layer near the PTL interface can alleviate the effect of mass transfer performance and improve the performance. The internal voltage loss of the optimal MEA is 21.5% lower than the conventional single-layer catalyst layer MEA at 3 A cm‐2.

Ru-Ce0.7Zr0.3O2-δ as an Anode Catalyst for the Internal Reforming of Dimethyl Ether in Solid Oxide Fuel Cells.

The development of direct dimethyl ether (DME) solid oxide fuel cells (SOFCs) has several drawbacks, due to the low catalytic activity and carbon deposition of conventional Ni-zirconia-based anodes. In the present study, the insertion of 2.0 wt.% Ru-Ce0.7Zr0.3O2-δ (ruthenium-zirconium-doped ceria, Ru-CZO) as an anode catalyst layer (ACL) is proposed to be a promising solution. For this purpose, the CZO powder was prepared by the sol-gel synthesis method, and subsequently, nanoparticles of Ru (1.0-2.0 wt.%) were synthesized by the impregnation method and calcination. The catalyst powder was characterized by BET-specific surface area, X-ray diffraction (XRD), field emission scanning electron microscopy with an energy-dispersive spectroscopy detector (FESEM-EDS), and transmission electron microscopy (TEM) techniques. Afterward, the catalytic activity of Ru-CZO catalyst was studied using DME partial oxidation. Finally, button anode-supported SOFCs with Ru-CZO ACL were prepared, depositing Ru-CZO onto the anode support and using an annealing process. The effect of ACL on the electrochemical performance of cells was investigated under a DME and air mixture at 750 °C. The results showed a high dispersion of Ru in the CZO solid solution, which provided a complete DME conversion and high yields of H2 and CO at 750 °C. As a result, 2.0 wt.% Ru-CZO ACL enhanced the cell performance by more than 20% at 750 °C. The post-test analysis of cells with ACL proved a remarkable resistance of Ru-CZO ACL to carbon deposition compared to the reference cell, evidencing the potential application of Ru-CZO as a catalyst as well as an ACL for direct DME SOFCs.

1D Monoclinic IrxRu1‐xO2 Solid Solution with Ru‐Enhanced Electrocatalytic Activity for Acidic Oxygen Evolution Reaction

AbstractThe rutile phase IrO2, as a promising catalyst for oxygen evolution reaction (OER), still falls short of satisfactory activity. Here, a novel 1D monoclinic phase iridium‐ruthenium oxide solid solution (m‐IrxRu1‐xO2) is reported. For m‐IrxRu1‐xO2 with different metal proportions, the optimal m‐Ir0.91Ru0.09O2‐δ catalyst exhibits excellent OER activity under acidic conditions with an overpotential of 180 mV at 10 mA cm−2. As an anode catalyst in a proton exchange membrane electrolyzer, m‐Ir0.91Ru0.09O2‐δ with a low catalyst loading (0.1 mg cm−2) can operate ≈256 h at 1.8 V with a high current density over 900 mA cm−2 at room temperature. Such a satisfied stability may have originated from the specific morphology and crystal structure, which is confirmed by the transient potential scanning test. Density functional theory calculations show that the Ru in the m‐IrxRu1‐xO2 facilitates decreasing the OER overpotentials due to the electron transfer from Ru to Ir.

Formation of Disordered High-Entropy-Alloy Nanoparticles for Highly Efficient Hydrogen Electrocatalysis.

Nanoparticles composed of high-entropy alloys (HEA NPs) exhibit remarkable performance in electrocatalytic processes such as hydrogen evolution and oxidations. In this study, two types of quinary HEA NPs of PtRhPdIrRu, are synthesized, featuring disordered and crystallized nanostructures, both with and without a boiling mixture. The disordered HEA NPs (d-HEA NPs) with a size of 3.5nm is synthesized under intense boiling conditions, attributed to improved heat and mass transfer during reduction of precursors and particle growth. The disordered HEA NPs displayed an exceptionally high turnover frequency of 33.1s-1 at an overpotential of 50mV, surpassing commercial Pt NPs in acidic electrolytes by 5.4 times. Additionally, d-HEA NPs exhibited superior stability at a constant electrolyzing current of 50mA cm-2 compared to commercial Pt NPs. When employed as the anodic catalyst in an H2-O2 fuel cell, d-HEA NPs demonstrated a remarkable high current power density of 15.3kW per gram of noble metal. Consequently, these findings highlight the potential of d-HEA NPs in electrochemical applications involving hydrogen.

Highly efficient metal free aldehyde-functionalized indoles for direct glucose fuel cell anode catalyst

In this study, alternative organic catalysts to metal-containing catalysts for glucose electrooxidation were prepared by the Suzuki Miyaura coupling reaction method and characterized by nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FT-IR), and liquid chromatography with tandem mass spectrometry (LC-MS-MS). InTA-1, InPA-1, InFA-1, InTA-2, InPA-2, InFA-2, InTA-3, InFA-3, and InPA-3 were obtained with the yield of 74%, 82%, 72%, 70%, 75%, 68%, 60%, 71%, and 85%. Among the synthesized catalysts, the InTA-3 catalyst possesses the highest electrocatalytic activity (3.17 mA cm−2) and long-term stability compared to other organic catalysts. InTA-3 catalyst has the lowest charge transfer resistance toward glucose electrooxidation. It was concluded that as a metal-free catalyst, InTA-3 is a cheap and promising electrocatalyst for direct glucose fuel cell anode.

Unraveling the crucial contribution of additive chromate to efficient and stable alkaline seawater oxidation on Ni-based layered double hydroxides

Seawater electrolysis to generate hydrogen offers a clean, green, and sustainable solution for new energy. However, the catalytic activity and durability of anodic catalysts are plagued by the corrosion and competitive oxidation reactions of chloride in high concentrations. In this study, we find that the additive CrO42− anions in the electrolyte can not only promote the formation and stabilization of the metal oxyhydroxide active phase but also greatly mitigate the adverse effect of Cl− on the anode. Linear sweep voltammetry, accelerated corrosion experiments, corrosion polarization curves, and charge transfer resistance results indicate that the addition of CrO42− distinctly improves oxygen evolution reaction (OER) kinetics and corrosion resistance in alkaline seawater electrolytes. Especially, the introduction of CrO42− even in the highly concentrated NaCl (2.5 M) electrolyte prolongs the durability of NiFe-LDH to almost five times the case without CrO42−. Density functional theory calculations also reveal that the adsorption of CrO42− can tune the electronic configuration of active sites of metal oxyhydroxides, enhance conductivity, and optimize the intermediate adsorption energies. This anionic additive strategy can give a better enlightenment for the development of efficient and stable oxygen evolution reactions for seawater electrolysis.

Efficient and Stable Proton Exchange Membrane Water Electrolysis Enabled by Stress Optimization.

Proton exchange membrane water electrolysis (PEMWE) is a promising solution for the conversion and storage of fluctuating renewable energy sources. Although tremendously efficient materials have been developed, commercial PEMWE products still cannot fulfill industrial demands regarding efficiency and stability. In this work, we demonstrate that the stress distribution, a purely mechanical parameter in electrolyzer assembly, plays a critical role in overall efficiency and stability. The conventional cell structure, which usually adopts a serpentine flow channel (S-FC) to deliver and distribute reactants and products, resulted in highly uneven stress distribution. Consequently, the anode catalyst layer (ACL) under the high stress region was severely deformed, whereas the low stress region was not as active due to poor electrical contact. To address these issues, we proposed a Ti mesh flow channel (TM-FC) with gradient pores to reduce the stress inhomogeneity. Consequently, the ACL with TM-FC exhibited 27 mV lower voltage initially and an 8-fold reduction in voltage degradation rate compared to that with S-FC at 2.0 A/cm2. Additionally, the applicability of the TM-FC was demonstrated in cross-scale electrolyzers up to 100 kW, showing a voltage increase of only 20 mV (accounting for less than 2% of overall voltage) after three orders of magnitude scaleup.

Ultrathin amorphous NaIrRuOx nanosheets with rich oxygen vacancies for efficient acidic water oxidation

Developing highly active and durable catalysts for H2O/O2 conversion is particularly important in water electrolyzers for renewable hydrogen energy. Herein, we prepared ultrathin amorphous NaIrRuOx nanosheets (NSs) with a thickness of 1.2 nm with a large number of oxygen vacancies using a simple molten salt method. The NaIrRuOx NSs exhibits a low overpotential (η10, 10 mA cm−2) of 214 mV, and 8.6 and 45.7 times enhanced mass activitynoble metal at 1.53 V vs. RHE, as compared to the commercial RuO2 and IrO2, respectively. Furthermore, the NaIrRuOx NSs shows excellent corrosion and oxidation resistance in acidic oxygen evolution reaction (OER), as confirmed by a negligible potential increase after 100 h of continuous electrolysis. In a homemade PEMWE, a membrane electrode using NaIrRuOx NSs as the anode catalyst can achieve cell voltages of 1.74 V at 1 A cm−2 and operate stably at 1 A cm−2 for 350 h. Theoretical calculations indicated that the intercalation of Na+ into IrRuOx weakens the adsorption strength of OER intermediates, thus reducing the energy consumption in the conversion from O* to OOH*, and thus significantly improving the OER performance.

Constructing Robust 3D Ionomer Networks in the Catalyst Layer to Achieve Stable Water Electrolysis for Green Hydrogen Production.

The widespread application of proton exchange membrane water electrolyzers (PEMWEs) is hampered by insufficient lifetime caused by degradation of the anode catalyst layer (ACL). Here, an important degradation mechanism has been identified, attributed to poor mechanical stability causing the mass transfer channels to be blocked by ionomers under operating conditions. By using liquid-phase atomic force microscopy, we directly observed that the ionomers were randomly distributed (RD) in the ACL, which occupied the mass transfer channels due to swelling, creeping, and migration properties. Interestingly, we found that alternating treatments of the ACL in different water/temperature environments resulted in forming three-dimensional ionomer networks (3D INs) in the ACL, which increased the mechanical strength of microstructures by 3 times. Benefitting from the efficient and stable mass transfer channels, the lifetime was improved by 19 times. A low degradation rate of approximately 3.0 μV/h at 80 °C and a high current density of 2.0 A/cm2 was achieved on a 50 cm2 electrolyzer. These data demonstrated a forecasted lifetime of 80 000 h, approaching the 2026 DOE lifetime target. This work emphasizes the importance of the mechanical stability of the ACL and offers a general strategy for designing and developing a durable PEMWE.

Highly active polyethylene glycol grafted cellulose supported Pd nanoparticles for glucose electrooxidation

In this study, poly(ethylene glycol) (PEG) grafted cellulose (CE) composite catalyst support material (PEG-CE) was obtained by chemically cross-linking PEG at varying molecular weight and CE with isophorone diisocyanate (IPDI) and 2,4-toluylene diisocyanate (TDI). PEG-CE supported Pd (Pd/PEG-CE) catalyst was prepared by the chemical reduction method. The crystal size of the Pd/PEG-CE catalyst is 4.79 nm and its crystal structure has been determined to be face-centered cubic Pd. Elemental mapping results indicate that Pd was reduced onto PEG-CE successfully and uniformly. Pd exists in the elemental and Pd-O form in the catalyst system. The Pd loading rate of Pd/PEG-C_IPDI catalyst was determined as 18.8% by mass. Among the PEG-CEs prepared with TDI and IPDI, PEG4000-CE_TDI and PEG6000-CE_IPDI displayed the highest specific activities of 1.03 and 1.50 mA cm−2 for glucose electrooxidation. With Pd reduction on PEG4000-CE_TDI and PEG6000-CE_IPDI, the specific activities increased to 1.62 mA cm−2 and 6.97 mA cm‐2. Pd/PEG6000-CE_IPDI has the highest electrocatalytic activity and stability in this study for glucose electrooxidation and is an encouraging anode catalyst for direct glucose fuel cells.

Effect of air depletion in the preferential oxidation reactor and fuel depletion in a proton exchange membrane fuel cell system fueled by natural gas

This study estimates the steady-state performance of a proton exchange membrane fuel cell (PEMFC) under conditions of air depletion in the preferential oxidation reactor (PrOx) and fuel depletion at the anode, which has not been previously studied. Considering the detailed chemical reactions of the reforming process, the composition of the reformed gas at the anode inlet is determined using the temperature and pressure data measured at various state points in the PEMFC system. To calculate the voltage loss at the anode due to the air depletion in PrOx or reformate gas depletion before the anode, the electrochemical reaction of the reformed gas in the anode catalyst layer is studied. The calculations show that when the fuel entering the anode or air entering the PrOx decreases, the amount of CO at the anode increases depending on the reduction, resulting in activation loss at the anode, and thereby leading to power loss. This analysis of the power loss in a PEMFC due to a lack of air or fuel can serve as an auxiliary diagnostic tool to identify faulty parts in the Balance of Plant (BOP).

Local coordination and electronic interactions of Pd/MXene via dual‐atom codoping with superior durability for efficient electrocatalytic ethanol oxidation

AbstractCatalyst design relies heavily on electronic metal‐support interactions, but the metal‐support interface with an uncontrollable electronic or coordination environment makes it challenging. Herein, we outline a promising approach for the rational design of catalysts involving heteroatoms as anchors for Pd nanoparticles for ethanol oxidation reaction (EOR) catalysis. The doped B and N atoms from dimethylamine borane (DB) occupy the position of the Ti3C2 lattice to anchor the supported Pd nanoparticles. The electrons transfer from the support to B atoms, and then to the metal Pd to form a stable electronic center. A strong electronic interaction can be produced and the d‐band center can be shifted down, driving Pd into the dominant metallic state and making Pd nanoparticles deposit uniformly on the support. As‐obtained Pd/DB–Ti3C2 exhibits superior durability to its counterpart (∼14.6% retention) with 91.1% retention after 2000 cycles, placing it among the top single metal anodic catalysts. Further, in situ Raman and density functional theory computations confirm that Pd/DB–Ti3C2 is capable of dehydrogenating ethanol at low reaction energies.

Catalysts for Direct Seawater Electrolysis: Current Status and Future Prospectives

AbstractGlobal freshwater shortage is forcing researchers to focus on seawater electrolysis for large‐scale green hydrogen production. Seawater purification by reverse osmosis (RO) for use in conventional water electrolyzers (WEs) is another approach, however, that requires large capital investments. Alternatively, seawater can be used directly in a novel type of anion exchange membrane WE (AEMWE) which is currently under development. The AEMWEs have the advantage of using non‐precious catalysts and are less sensitive to the presence of impurities. Success in this early‐stage technology relies on the development of efficient and durable electrocatalysts. This paper provides a comprehensive review of the status and future trends for developing catalysts operating directly with seawater. Catalysts are ranked based on their activity and durability at high current densities of 500 mAcm−2 and 1000 mAcm−2. Notable anode catalysts, S−NiFe2O4, and NiFe LDH, exhibit reduced OER overpotentials of 287 mV and 296 mV at 1000 mAcm−2. Top‐performing cathode HER catalysts include HW−NiMoN‐2 h (132 mV) and Pt−Co−Mo (117 mV) at 1000 mAcm−2. Bifunctional catalysts, such as CoxPv@NC can operate below an overall voltage of 2 V at 1000 mAcm−2. This comparative analysis provides researchers and professionals with critical insights for advancing direct seawater electrolysis.

Screening reversal tolerance through rotating disc electrode studies

Anode reversal is a detrimental phenomenon that occurs in proton exchange membrane fuel cells (PEMFCs) when the anode is subject to fuel starvation, leading to irreversible damage. This is a critical issue for the commercialization of PEMFCs. However, the development of more robust anode catalysts has been limited by the need for membrane electrode assembly (MEA)-level testing, which is costly and time-consuming. Here, we propose two accelerated stress test (AST) protocols based on widely available rotating disc electrode (RDE) methods to determine their suitability for screening anode catalysts and predicting MEA-level durability. One method is based on a carbon corrosion (cc) voltage cycling protocol between 1.0 and 1.5 V vs. RHE, while the other is a chronopotentiometry (cp) method. We evaluate three model catalysts (Pt30, Pt50, and Pt70) at the MEA-level through standard reversal testing and at the RDE-level using the two AST protocols (RDE-cc and RDE-cp). We find that both RDE-level methods can reliably predict MEA-level anode durability, and can be used by materials scientists to screen the relative durability of new anode catalysts. Our results also suggest Pt70 is a promising candidate for anode reversal tolerant PEMFCs, as it shows superior durability under both MEA-level and RDE-level tests.

Porous hemispherical Au@PdAg catalysts for enhancing ethanol electrooxidation

Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (COads) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd1.0Ag1.0 has the highest mass current density with a peak value of 4048.8 mAmgPd−1, which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mAmgPd−1. The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OHads and the oxidation of COads. The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability.

Coupling electrocatalytic CO2 reduction with glucose oxidation for concurrent production of formate with high efficiency

Electrocatalytic reduction of CO2 (CO2ER) coupled with the oxygen evolution reaction (OER) is an energy-intensive process that generates low-value oxygen, limiting its industrial application. To overcome this limitation, here we report a membrane electrode assembly (MEA) system that combines CO2ER with glucose electrooxidation (GEOR) to simultaneously produce formate using bismuth subcarbonate and carbon nanotube hybrid (BOC-CNT) and nickel cobalt oxide decorated on carbon fiber paper (NCO-CFP) as the cathode and anode catalysts, respectively. The BOC-CNT catalyst showed excellent electrocatalytic performance for CO2ER to formate, affording a high FEHCOO- of 97.9 % with current density of 360 mA cm−2 at −0.77 V vs. RHE (-580 mV overpotential), and the NCO-CFP catalyst achieved GEOR at 0.99 V (vs. RHE) with FEHCOO- >98 %. The coupled CO2ER//GEOR MEA exhibits a low onset cell voltage of 1.20 V and reaches ultrahigh apparent Faraday efficiency of formate (>190 %) in a wide range from 1.8 to 2.4 V, achieving ∼ 33.3 % energy savings compared to CO2ER//OER with a high formate yield of 0.92 mol g-1h−1 at 100 mA cm−2. Besides, all generated formate can be collected from the electrolyte on the anode side due to the spontaneous migration of formate under electric field, thus reducing cross-contamination from CO2 and alkaline electrolytes. In addition, the coupled CO2ER//GEOR system exhibited good electrocatalytic stability for at least 32 h. This strategy provides an innovative and promising approach for the co-electrolytic transformation of biomass derivatives and CO2 to formate.

Microscopic-Level Insights into P-O-Induced Strong Electronic Coupling Over Nickel Phosphide with Efficient Benzyl Alcohol Electrooxidation.

Electrooxidation of biomass into fine chemicals coupled with energy-saving hydrogen production for a zero-carbon economy holds great promise. Advanced anode catalysts determine the cell voltage and electrocatalytic efficiency greatly, further the rational design and optimization of their active site coordination remains a challenge. Herein, a phosphorus-oxygen terminals-rich species (Ni2P-O-300) via an anion-assisted pyrolysis strategy is reported to induce strong electronic coupling and high valence state of active nickel sites over nickel phosphide. This ultimately facilitates the rapid yet in-situ formation of high-valence nickel with a high reaction activity under electrochemical conditions, and exhibits a low potential of 1.33V vs. RHE at 10mAcm-2, exceeding most of reported transition metal-based catalysts. Advanced spectroscopy, theoretical calculations, and experiments reveal that the functional P-O species can induce the favorable local bonding configurations for electronic coupling, promoting the electron transfer from Ni to P and the adsorption of benzyl alcohol (BA). Finally, the hydrogen production efficiency and kinetic constant of BA electrooxidation by Ni2P-O-300 are increased by 9- and 2.8- fold compared with the phosphorus-oxygen terminals-deficient catalysts (Ni2P-O-500). This provides an anion-assisted pyrolysis strategy to modulate the electronic environment of the Ni site, enabling a guideline for Ni-based energy/catalysis systems.

Heterointerface engineering of rhombic Rh nanosheets confined on MXene for efficient methanol oxidation

Although metallic rhodium (Rh) is regarded as a promising platinum-alternative anode catalyst of direct methanol fuel cell (DMFC), the conventional “particle-to-face” contact model between Rh and matrix largely limits the overall electrocatalytic performance due to their insufficient cooperative effects. Herein, we report a controllable and robust heterointerface engineering strategy for the bottom-up fabrication of rhombic Rh nanosheets in situ confined on Ti3C2Tx MXene nanolamellas (Rh NS/MXene) via a convenient stereoassembly process. This unique design concept gives the resulting 2D/2D Rh NS/MXene heterostructure intriguing textural features, including large accessible surface areas, strong “face-to-face” interfacial interactions, homogeneous Rh nanosheet distribution, ameliorative electronic structure, and high electronic conductivity. As a consequence, the as-prepared Rh NS/MXene nanoarchitectures exhibit exceptional electrocatalytic methanol oxidation properties in terms of a large electrochemically active surface area of 126.2 m2 g−1Rh, a high mass activity of 1056.9 mA mg−1Rh, and a long service life, which significantly outperform those of conventional particle-shaped Rh catalysts supported by carbon black, carbon nanotubes, reduced graphene oxide, and MXene matrixes as well as the commercial Pt nanoparticle/carbon black and Pd nanoparticle/carbon black catalysts with the same noble metal loading amount. Density functional theory calculations further demonstrate that the direct electronic interaction at the well-contacted 2D/2D heterointerfaces effectively enhances the adsorption energy of Rh nanosheets and induces a left shift of the d-band center, thereby making the Rh NS/MXene configuration suffer less from CO poisoning. This work highlights the importance of rational heterointerface design in the construction of advanced noble metal/MXene electrocatalysts, which may provide new avenues for developing the next-generation DMFC devices.

Deposition and removal of manganese oxide in zinc electrowinning

Zinc electrowinning in sulfate-based electrolytes produces zinc at the cathode and oxygen gas at the anode. Lead anodes are commonly used despite its low activity towards oxygen evolution and potential environmental hazards. Recent advances in materials for oxygen evolution in acidic electrolytes offers a wide variety of alternative anode catalysts with much higher performance than lead. However, significant formation of manganese oxide alongside oxygen evolution at the anode prevents introduction of new and more active catalytic coatings. In this work, we investigate manganese oxide deposition at IrO2Ta2O5 coated Ti electrodes using chronoamperometry, linear sweep voltammetry and rotating disc electrode. The morphologies of the electrode and deposited manganese oxide are also examined. Oxygen evolution is observed to primarily occur at the electrode and not on the growing manganese oxide deposit. We provide experimental evidence that deposition of manganese oxide gradually becomes limited by diffusion of Mn2＋ within the growing manganese oxide deposit itself. We interpret this to be due to formation of a poorly conducting outer part of the deposit. An electrochemical sequence for removal of deposited manganese oxide is developed and validated in synthetic electrolyte (2molL-1 H2SO4 + 0.15molL-1 Mn2+) and industrial electrolyte. Most importantly the sequence includes formation of a prelayer of manganese oxide at a low electrode potential (1000s at 1.45V or 7Am−2) as we show this to reduce more easily. Furthermore, a short reduction step (100s at 0.4V or −35Am−2) is then sufficient to diminish the adhesion of remaining manganese oxide and allow for easy mechanical removal. Implementing this method can make it possible to replace the currently used anodes in zinc electrowinning with more energy efficient and environmentally friendly anodes.