Boosting high-current alkaline water electrolysis and carbon dioxide reduction with novel CuNiFe-based anodes

The transition to a green hydrogen economy demands robust, scalable, and sustainable anodes for alkaline water electrolysis operating at industrial current densities (>1 A/cm2). However, achieving high activity and long-term stability under such conditions remains a formidable challenge with conventional catalysts. Here, we report a novel trimetallic CuNiFe anode fabricated through a rapid, single-step electrodeposition process at room temperature without organic additives. The catalyst exhibits an exceptionally low overpotential of <270 mV at 100 mA cm(-2) and operates stably for over 500 hours at 1 A cm(-2) in 30 wt% KOH. In a practical anion exchange membrane water electrolyzer (AEM-WE), the CuNiFe anode enables a current density of 2.5 A cm(-2) at only 2.5 V, with a voltage efficiency of 66.8%. Beyond water splitting, this anode also significantly enhances CO2 electrolysis, tripling the CO2 reduction current density and steering selectivity toward valuable multi-carbon products when paired with commercial copper cathodes. A cradle-to-gate life cycle assessment confirms that the CuNiFe anode reduces the carbon footprint by an order of magnitude and decreases environmental impacts by 40-60% across multiple categories compared to benchmark IrRuO2. Our work establishes a scalable, high-performance, and environmentally benign anode technology, paving the way for cost-effective electrochemical production of green hydrogen and carbon-neutral chemicals.

💡 Research Summary

This paper presents a novel trimetallic Cu–Ni–Fe (CuNiFe) anode designed for high‑current alkaline water electrolysis (AWE) and carbon dioxide (CO₂) reduction, addressing the critical need for robust, scalable, and low‑cost catalysts capable of operating at industrial current densities (>1 A cm⁻²). The authors develop a rapid, single‑step electrodeposition method performed at room temperature without organic additives. By pulsing a cathodic current of –100 mA cm⁻² (ON 0.5 s, OFF 0.05 s) for 150 s onto a nickel foam substrate immersed in a solution containing 5 mM Cu²⁺, 5 mM Ni²⁺, 5 mM Fe³⁺ and 30 mM H₂SO₄ in 1 M KOH, a uniform CuNiFe film is formed in under five minutes. Structural characterization (XRD, SEM, TEM, HR‑TEM, EDS, XPS) reveals a composite of NiCuFeO₂, metallic Cu, and Ni‑Fe layered double hydroxide (LDH) nanocrystals with particle sizes ranging from 5 to 20 nm (average ≈11 nm). The metallic Cu core provides high electronic conductivity, while the Ni‑Fe LDH shells supply abundant active sites and facilitate charge transfer at the electrode/electrolyte interface.

Electrochemical testing in 1 M KOH shows an overpotential of <270 mV at 100 mA cm⁻², which is 130–200 mV lower than conventional Ni mesh, IrO₂‑GDE, or pure Ni‑Fe LDH electrodes. At 1 A cm⁻² in 30 wt% KOH, the CuNiFe anode operates stably for more than 500 h with a voltage drift of <10 µV h⁻¹ and no detectable metal leaching (ICP‑MS). In an anion‑exchange‑membrane water electrolyzer (AEM‑WE) operated at 60 °C, the anode delivers 2.5 A cm⁻² at a cell voltage of 2.5 V, corresponding to a voltage efficiency of 66.8 %—a performance level that meets or exceeds industrial targets while using a far cheaper catalyst than noble‑metal oxides.

When paired with a commercial copper cathode for CO₂ electroreduction, the CuNiFe anode triples the total reduction current density and shifts product distribution toward valuable C₂⁺ species (ethylene, ethanol, acetate). The authors attribute this to enhanced OH⁻ supply and reduced interfacial resistance, which promote *CO intermediate coupling on the copper cathode.

A cradle‑to‑gate life‑cycle assessment (LCA) compares the CuNiFe anode to a benchmark IrRuO₂ electrode. The LCA accounts for raw material extraction, electrode fabrication, operation, and end‑of‑life. Because the CuNiFe anode uses inexpensive base metals, requires only a 5‑minute low‑energy deposition step, and exhibits superior durability, its total carbon footprint is reduced by an order of magnitude. Environmental impact categories (global warming potential, mineral depletion, human toxicity, etc.) improve by 40–60 % relative to the IrRuO₂ reference.

Overall, the study demonstrates that the CuNiFe anode simultaneously achieves (i) ultra‑fast, additive‑free, scalable synthesis, (ii) low overpotential and high current density operation with >500 h durability, (iii) excellent performance in practical AEM‑WE cells, (iv) significant enhancement of CO₂ reduction to multi‑carbon products, and (v) a markedly lower environmental burden. These attributes position the CuNiFe anode as a compelling candidate for large‑scale, cost‑effective production of green hydrogen and carbon‑neutral chemicals, potentially accelerating the transition to a sustainable energy economy.