A team of researchers in China has engineered a nickel-doped copper catalyst derived from metal-organic frameworks that converts carbon dioxide into ethylene and other multi-carbon chemicals with notably high efficiency and remarkable stability, offering a fresh strategy for one of the most stubborn challenges in electrochemistry. The work, published in Catalysis Letters, addresses a long-standing bottleneck in carbon dioxide electroreduction, the process by which electricity—ideally from renewable sources—drives the transformation of carbon dioxide into fuels and industrial feedstocks. While copper remains the only metal known to catalyze the formation of carbon-carbon bonds from carbon dioxide at appreciable rates, pure copper electrodes tend to produce a messy mixture of products, including hydrogen gas, carbon monoxide, formate, methane, and small amounts of ethylene. Directing the reaction selectively toward valuable multi-carbon products such as ethylene has proved extremely difficult, and it is precisely this selectivity problem that the new study set out to solve.
The researchers, led by Aicheng Song and corresponding author Zhitao Han of the Marine Engineering College at Dalian Maritime University, together with colleagues at Harbin Engineering University, synthesized a family of nickel-modified copper-based metal-organic frameworks using a solvothermal method, in which the framework precursors are crystallized from a hot organic solvent. Metal-organic frameworks, or MOFs, are crystalline lattices in which metal ions or clusters are linked by organic ligands into highly ordered, porous architectures. Their appeal as catalyst precursors lies in two properties: their metal centers can be arranged with atomic precision, and their pores create an enormous internal surface area. The team then subjected these frameworks to calcination—heating under controlled conditions—to produce derivative catalysts in which the original structure transforms into a more robust, conductive form while retaining the porosity and bimetallic intimacy of the parent framework. By tuning the nickel content, they generated a series of samples designated by increasing nickel loading, culminating in the optimized catalyst labeled CuNi-2.
The performance figures reported for CuNi-2 are striking. At an applied potential of -1.0 volts versus a reversible hydrogen electrode, a standard reference condition in electrocatalysis, the catalyst achieved a Faradaic efficiency of 55.56 percent for multi-carbon products overall and 32.35 percent for ethylene specifically. Faradaic efficiency, also called Faraday efficiency, measures the fraction of electrical current that goes into making a given product rather than into competing side reactions; values above 50 percent for multi-carbon products on a MOF-derived copper system represent a meaningful advance. Equally important, the catalyst sustained its activity over 40 hours of continuous operation without significant degradation. Durability is often the Achilles heel of MOF-derived catalysts, which can restructure, sinter, or leach under the harsh reducing potentials required for carbon dioxide reduction, so a 40-hour stability test provides reassurance that the bimetallic architecture is not merely a transient arrangement of atoms but a genuinely robust catalytic system.
The central scientific insight of the study concerns the electronic interplay between nickel and copper. Through a battery of characterization techniques—including X-ray diffraction to determine crystal structure, scanning electron microscopy and energy dispersive X-ray spectroscopy to map morphology and elemental distribution, X-ray photoelectron spectroscopy to probe surface chemistry, and electrochemical measurements such as linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy—the researchers showed that nickel doping does not simply add a second catalytic site. Instead, it modulates the electronic structure of the copper itself. Nickel atoms, embedded within the copper lattice or in close bimetallic proximity, shift the electron density around copper atoms in ways that stabilize the Cu+ oxidation state at the catalyst surface. That stabilization matters because Cu+ species are widely believed to be key active sites for carbon-carbon coupling; plain copper surfaces tend to lose Cu+ to metallic Cu0 under working conditions, which favors single-carbon products and hydrogen evolution instead.
The second consequence of this electronic tuning is an enriched surface coverage of adsorbed carbon monoxide, the CO intermediate, on the catalyst surface. In the generally accepted mechanism of carbon dioxide electroreduction on copper, carbon dioxide is first converted to CO, and two neighboring CO species must then couple to form a OCCO dimer, the critical carbon-carbon bond-forming step on the road to ethylene. The rate of that coupling depends on both the thermodynamic tendency of CO species to bind to the surface and their local concentration. By stabilizing Cu+ sites and tuning the binding energy of CO, nickel doping raises the surface CO coverage, bringing neighboring intermediates close enough to dimerize efficiently. At the same time, the doping adjusts the CO binding strength into a favorable window: if *CO binds too weakly it desorbs as carbon monoxide gas before coupling, and if it binds too strongly it poisons the surface. The nickel-modified copper appears to sit near the optimum of this balance, which explains the shift in selectivity from single-carbon products toward ethylene.
The porous architecture inherited from the MOF template provides a complementary advantage. Because the calcined catalyst retains an open, hierarchical pore network, carbon dioxide can diffuse rapidly to active sites and the gaseous products can escape, improving mass transport at high current densities. Just as importantly, the confined pore spaces act as nanoscale reactors that trap reactive intermediates near one another, effectively raising their local concentration and further promoting the carbon-carbon coupling step. This dual function—facilitating transport while confining intermediates—illustrates why MOF-derived catalysts have attracted such intense interest: the template strategy decouples, to some degree, the need for high surface area from the need for a specific surface chemistry, allowing both to be engineered simultaneously. The team’s systematic comparison across the series of nickel loadings showed that selectivity for multi-carbon products peaked at an intermediate composition, consistent with the picture of an optimal electronic and structural balance rather than a simple monotonic effect.
The broader context makes the result timely. Ethylene is the world’s most produced organic chemical, serving as the feedstock for polyethylene and countless other polymers, and it is currently made almost exclusively from petroleum cracking at high temperatures. A route that converts carbon dioxide into ethylene using renewable electricity would simultaneously recycle a greenhouse gas and displace a fossil-intensive process. The obstacle has always been economics: electrosynthesis of ethylene must compete with petrochemical prices, which demands high selectivity, high current density, and long catalyst lifetimes all at once. Recent years have seen rapid progress on copper catalysts—oxide-derived copper, grain-engineered foils, molecular additives, and tandem catalysts—but each strategy carries trade-offs in cost, scalability, or stability. The bimetallic electronic modulation strategy demonstrated here, in which a cheap and earth-abundant dopant (nickel) tunes an abundant host (copper) within a scalable MOF-templated synthesis, offers a comparatively simple and industrially plausible route to the same goal.
The study’s diagnostic toolkit also provides a methodological template for the field. By combining X-ray photoelectron spectroscopy, which quantifies the Cu+ to Cu0 ratio at the surface, with product analysis by gas chromatography and nuclear magnetic resonance of the liquid phase, the researchers could correlate the oxidation-state balance with Faradaic efficiencies across the catalyst series. Electrochemical impedance spectroscopy revealed reduced charge-transfer resistance for the optimized sample, indicating that the bimetallic surface not only changes chemistry but also accelerates electron transfer to the adsorbed intermediates. Linear sweep voltammetry showed the onset of carbon dioxide reduction at more positive potentials for the nickel-doped catalyst, pointing to lowered activation barriers for the rate-determining steps. Taken together, the data build a coherent mechanistic narrative in which electronic structure, intermediate coverage, and pore architecture act in concert rather than in isolation.
There remain, of course, substantial hurdles between a laboratory cell and a commercial reactor. The reported Faradaic efficiency of 55.56 percent for multi-carbon products, while impressive, still leaves nearly half of the current consumed by hydrogen evolution and single-carbon byproducts, and industrial deployment would require pushing combined selectivity and current density considerably higher while maintaining stability over thousands of hours. The experiments were conducted under the well-controlled conditions of a standard three-electrode or flow-type electrochemical setup, and real devices with gas-diffusion electrodes, recycled electrolytes, and fluctuating renewable power will impose additional stresses. Nevertheless, the 40-hour durability result and the mechanistic clarity of the electronic modulation argument give the approach credibility, and the general strategy—doping a copper MOF with a second metal chosen for its electronic effect—can in principle be extended to other dopants, other frameworks, and other target products such as ethanol, acetate, or propanol.
The work was supported by the National Natural Science Foundation of China under grant 52271356, and the authors report no competing interests. For a field racing to turn waste carbon dioxide into the building blocks of modern industry, the Dalian Maritime University and Harbin Engineering University team has contributed a conceptually clean demonstration: that the selectivity of copper is not fixed destiny but a tunable property, adjustable one electron at a time through a carefully chosen atomic neighbor. If subsequent studies can translate this bimetallic MOF-derived platform to industrially relevant current densities, the humble pairing of copper and nickel inside a porous framework may prove to be one of the more consequential recipes in the emerging toolbox of carbon-neutral chemical manufacturing.
Subject of Research: Nickel-doped copper-based metal-organic framework catalysts for electrochemical CO2 reduction to multi-carbon products, particularly ethylene.
Subject of Research: Chemistry
Article Title: Modulating Electronic Structure of Cu-Based MOF via Ni Doping for Efficient CO2 Electroreduction to C2+ Products
Article References: Song, A., Han, Z., Zhang, M., Yang, X., Yan, B., Liu, D., & Zhou, S. (2026). Modulating Electronic Structure of Cu-Based MOF via Ni Doping for Efficient CO2 Electroreduction to C2+ Products. Catalysis Letters, 156(9), Article 262. https://doi.org/10.1007/s10562-026-05506-1
Image Credits: AI Generated
DOI: 10.1007/s10562-026-05506-1
Keywords: CO2 reduction, Ethylene, Bimetallic catalyst, MOF derivatives, Electrocatalysis, Copper catalyst, Nickel doping, Faradaic efficiency, C-C coupling, Cu+ active species, Carbon dioxide electroreduction
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Bethany Barker. (September 10, 2026). Nickel Doping in Copper MOF Boosts CO2 Conversion to C2+ Products. Scienmag. https://scienmag.com/nickel-doping-in-copper-mof-boosts-co2-conversion-to-c2-products/
Bethany Barker. “Nickel Doping in Copper MOF Boosts CO2 Conversion to C2+ Products.” Scienmag, 10 September 2026, https://scienmag.com/nickel-doping-in-copper-mof-boosts-co2-conversion-to-c2-products/. Accessed 10 September 2026.
Bethany Barker. “Nickel Doping in Copper MOF Boosts CO2 Conversion to C2+ Products.” Scienmag. September 10, 2026. https://scienmag.com/nickel-doping-in-copper-mof-boosts-co2-conversion-to-c2-products/
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