Laser-Tuned Platinum-Copper Electrodes Turn CO2 Into Ethylene and Ethanol

Turning carbon dioxide back into useful chemicals is one of the most tantalizing goals in modern electrochemistry, and copper has long been the star of the show. It is the only metal that reliably converts CO2 into a whole family of multi-carbon products, from ethylene to ethanol. But copper has a stubborn problem: it rarely makes just one thing. A team of researchers at Chungnam National University in South Korea now reports a strikingly simple way to steer copper’s product slate with a beam of light. By sputtering a whisper-thin layer of platinum onto copper foil and then sweeping lasers of two different wavelengths across the surface, they engineered interfaces that dramatically reshape what comes out of the electrochemical cell.

The study, published in Advances in Industrial and Engineering Chemistry, describes electrodes made by ion-sputtering platinum onto polished copper foil for either 10 or 60 seconds, followed by laser treatment with a 450 nm diode laser or a 1064 nm fiber laser. The researchers systematically varied laser power, scan speed, and treatment pattern, then ran one-hour electrolysis experiments at fixed potentials in three different electrolytes: potassium bicarbonate, potassium carbonate, and potassium phosphate buffer. Products were quantified with gas chromatography for gases and proton NMR spectroscopy for liquids, capturing everything from hydrogen and methane to propanol and even glycolaldehyde.

The headline result is the transformation of the platinum-coated copper electrode. Without laser treatment, the 60-second Pt/Cu electrode was essentially a hydrogen factory, producing hydrogen at roughly 69 percent Faradaic efficiency and formate as its only liquid product. After treatment with the 1064 nm laser at full power, hydrogen evolution collapsed to about 26 percent, and the electrode suddenly began producing ethanol at 10.7 percent, propanol at 6.8 percent, methanol, and acetate. Ethylene production jumped roughly twelvefold, from 0.93 percent to 12.27 percent Faradaic efficiency. In other words, a laser scan converted a nearly inert, hydrogen-spewing surface into a genuine carbon-carbon coupling catalyst.

Wavelength mattered enormously. The 450 nm laser, which transfers energy to the copper substrate less efficiently, produced no visible nanostructures under electron microscopy and only modest changes in product distribution. The 1064 nm laser, by contrast, blanketed the surface with dense spherical nanoparticles and triggered the biggest selectivity shifts. On bare copper, 1064 nm treatment boosted ethylene to 12.1 percent and pushed total long-chain hydrocarbon yields up about tenfold. The authors attribute these differences to how effectively each wavelength melts, ablates, and oxidizes the thin metal films, creating distinct populations of active sites.

Perhaps the most surprising discovery came from a fine-grained sweep of 1064 nm laser power between 20 and 30 percent. In that narrow window, the product palette exploded. At 25 percent power, ethanol peaked at nearly 19 percent and acetate at 3.5 percent. From 26 percent onward, propanol, isopropanol, methanol, and acetaldehyde all appeared, with isopropanol and acetaldehyde detected only within the 26 to 30 percent range. This razor-thin sensitivity suggests that the density and spacing of laser-generated nanoparticles, rather than bulk composition alone, control which carbon-carbon coupling pathways are accessible. It also hints at a practical dial: turn the laser power up or down and the electrode’s product portfolio changes accordingly.

The researchers frame their findings through the lens of electrochemical Fischer-Tropsch chemistry, the same chain-growth logic that governs industrial synthesis of fuels from syngas. By fitting Anderson-Schulz-Flory plots to their hydrocarbon distributions, they found that although alkanes have a slightly higher intrinsic chain-growth probability, hydrogenation is kinetically hindered at strongly reducing potentials. The practical consequence is that laser-treated surfaces favor unsaturated products: the alkene-to-alkane ratios for both C2 and C3 products rose consistently after laser treatment, with C3 ratios climbing to around ten at 1064 nm. Higher laser power appears to suppress post-coupling hydrogenation, letting ethylene and propene desorb before they can be saturated into ethane and propane.

Applied potential added another layer of control. On laser-patterned electrodes, formate was the sole liquid product at mild potentials of minus 1.4 to minus 1.6 volts, but from minus 1.8 volts onward the full liquid spectrum emerged, including propanol peaking at 7.4 percent, ethanol holding steady at 7 to 9 percent, and, uniquely at minus 2.2 volts, acetaldehyde and glycolaldehyde. Ethylene climbed roughly twelvefold across the potential window, while methane rose steadily to about 6 percent at the most negative potentials. Electrolyte concentration worked in the opposite direction: dilute 0.05 M bicarbonate maximized long-chain hydrocarbons and product diversity, while concentrated 0.5 M electrolyte drove hydrogen evolution to a crushing 95 percent on the platinum-coated electrode, leaving only formate behind.

Electrochemical diagnostics revealed why laser power demands such careful tuning. Double-layer capacitance measurements showed that moderate 50 percent laser power maximized the electrochemical surface area at roughly 16 square centimeters, while full-power treatment flattened the surface and shrank the active area to 3.24 square centimeters. Impedance spectroscopy told a two-sided story: excessive laser exposure built a thick, resistive oxide layer that impeded electron transport, yet simultaneously created a porous morphology that improved mass transport of reactants. Linear sweep voltammetry confirmed that the fully treated electrode delivered the highest cathodic currents near minus 2 volts, likely thanks to that oxide-rich surface, even as its conductivity suffered.

Depth-profiled X-ray photoelectron spectroscopy peeled back the chemical story layer by layer. On untreated Pt/Cu electrodes, the surface carried a mix of metallic platinum, oxidized platinum, and copper oxides, all of which were partially reduced during electrolysis. On laser-treated electrodes, the picture changed radically: the platinum signal nearly vanished at the surface, indicating the laser had stripped or thinned the overlayer, while copper was locked in a clean metallic state that resisted oxidation throughout the reaction. Ion scattering spectroscopy, reflected electron energy loss spectroscopy, and ultraviolet photoelectron spectroscopy corroborated this picture, and the reappearance of faint platinum signals after electrolysis hinted at subtle platinum rearrangement under operating conditions. Crucially, depth profiling confirmed that platinum survived on the electrode, proving the activity truly arises from the engineered Pt/Cu composite rather than bare copper alone.

What makes this work resonate beyond one laboratory is its manufacturing logic. Laser ablation requires no chemical baths, no exotic precursors, and no vacuum deposition beyond a simple sputtering step, and it scales naturally to large electrode areas with excellent reproducibility. As the authors conclude, the technique offers a scalable, non-chemical route to bimetallic interfaces whose electronic structure, oxidation state, and nanoscale texture can all be dialed in with a programmable beam. For a field racing to convert captured CO2 into ethylene, ethanol, and higher alcohols at industrially meaningful rates, the idea that a laser engraver could serve as a catalyst design tool is an invitation to rethink how electrocatalysts are made.

Subject of Research: Laser-ablation interface engineering of Pt-deposited Cu electrodes for electrochemical CO2 reduction to multi-carbon products

Article Title: Interface engineering of Pt-deposited Cu electrodes via laser ablation for enhanced electrochemical CO2 reduction to multi-carbon products

Article References: Interface engineering of Pt-deposited Cu electrodes via laser ablation for enhanced electrochemical CO2 reduction to multi-carbon products. (n.d.). https://doi.org/10.1007/s44405-025-00019-8

Image Credits: AI Generated

DOI: 10.1007/s44405-025-00019-8

Keywords: electrochemical CO2 reduction, copper catalysts, platinum, laser ablation, ethylene, ethanol, Faradaic efficiency, C-C coupling, Fischer-Tropsch, bimetallic electrodes, XPS, electrocatalysis