{"id":174797,"date":"2026-03-24T07:20:00","date_gmt":"2026-03-24T06:20:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=174797"},"modified":"2026-03-17T13:31:39","modified_gmt":"2026-03-17T12:31:39","slug":"atomic-ratio-tuning-in-catalysts-controls-carbon-nanofiber-production-from-co2","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/atomic-ratio-tuning-in-catalysts-controls-carbon-nanofiber-production-from-co2\/","title":{"rendered":"Atomic ratio tuning in catalysts controls carbon nanofiber production from CO2"},"content":{"rendered":"\n\n\n

Most efforts to recycle CO\u2082 turn it into fuels or chemicals that release carbon back into the atmosphere within\u00a0months. A more permanent solution would convert it into a solid material that locks carbon away for decades.\u00a0Carbon\u00a0nanofibers<\/a>\u00a0are one such material. These nanoscale carbon structures already find use as concrete\u00a0additives, battery components, and textile sensors, applications where carbon remains sequestered.<\/p>\n\n\n\n

The idea of using captured CO\u2082 as a feedstock for solid carbon nanomaterials has been gaining traction. In\u00a0previous\u00a0Nanowerk Spotlights\u00a0we have reported on efforts that have shown that\u00a0carbon nanotubes derived from\u00a0atmospheric CO\u2082 can strengthen plastics<\/a>, and that\u00a0converted CO\u2082 into buckypaper through molten carbonate\u00a0electrolysis.<\/p>\n\n\n\n

Producing carbon nanofibers from CO\u2082, however, has proved difficult. Some methods yield disordered amorphous\u00a0carbon, while others require reactor temperatures above 750 \u00b0C.<\/p>\n\n\n\n

A study published in\u00a0Advanced Energy Materials\u00a0(“Co-Electrolysis of CO2\u00a0and H2O to Syngas on Bimetallic\u00a0PdxCu1-x\u00a0Catalysts for Tandem Thermochemical Conversion to Carbon Nanofibers<\/a>“) reports a two-stage tandem\u00a0process that operates at just 450 \u00b0C and ambient pressure. CO\u2082 and water first enter an electrolyzer that splits\u00a0them into a mixture of carbon monoxide and hydrogen, known as syngas. That syngas then flows into a\u00a0thermochemical reactor where it converts into crystalline carbon nanofibers.<\/p>\n\n\n

\n
\"Schematic
Schematic of the tandem electrochemical-thermochemical catalysis system. \u00a9 Wiley-VCH Verlag<\/figcaption><\/figure><\/div>\n\n\n

What makes the approach distinctive is how tightly the upstream catalyst controls the downstream outcome. By\u00a0adjusting the ratio of palladium to copper in a bimetallic electrocatalyst, the team altered how hydrogen absorbs\u00a0into the metal lattice, which shifted the gas composition leaving the electrolyzer, which in turn changed how fast\u00a0nanofibers grew in the reactor. A small atomic adjustment at one end of the process reshaped the solid product at\u00a0the other.<\/p>\n\n\n\n

The electrolyzer uses a zero-gap membrane electrode assembly, a design where CO\u2082 gas flows directly to the\u00a0cathode surface rather than dissolving in a liquid electrolyte. This eliminates the mass transport bottlenecks of\u00a0conventional laboratory cells and enables industrially relevant current densities. At the cathode, two reactions run\u00a0in parallel: CO\u2082 becomes carbon monoxide, and water splits into hydrogen. The combined gaseous output then\u00a0passes into a packed bed reactor loaded with an iron-cobalt catalyst on a cerium oxide support, where carbon\u00a0monoxide molecules react with each other or with hydrogen to deposit solid carbon.<\/p>\n\n\n\n

The team synthesized a series of palladium-copper alloy compositions on carbon supports, systematically varying\u00a0the palladium-to-copper atomic ratio. Palladium excels at reducing CO\u2082 to carbon monoxide, but its scarcity and\u00a0cost pose barriers to large-scale use. Alloying with copper offered a way to reduce palladium loading while tuning\u00a0product selectivity.<\/p>\n\n\n\n

Electrochemical testing revealed a peaked trend in CO production, with performance rising and then falling as\u00a0copper content increased. The Pd\u2080.\u2087Cu\u2080.\u2083 composition reached the maximum, delivering a CO partial current\u00a0density of 81.9 mA cm\u207b\u00b2 and a Faradaic efficiency (the fraction of electrical current producing the desired product)\u00a0of 64.8%. Raising the copper fraction further shifted output back toward hydrogen and, in copper-rich\u00a0formulations, toward methane and ethylene.<\/p>\n\n\n\n

The downstream nanofiber results did not follow a simple correlation with CO and hydrogen output. Although\u00a0Pd\u2080.\u2084Cu\u2080.\u2086 produced less syngas than the top electrochemical performer, it delivered the fastest nanofiber growth\u00a0at 4.5 g per gram of metal per hour. Gas analysis pointed to the reason: ethylene generated by copper-rich\u00a0catalysts was completely consumed once it reached the thermochemical reactor, accompanied by a sharp rise in\u00a0methane. Ethylene appears to act as a supplementary carbon source, feeding nanofiber growth through a\u00a0pathway unavailable to syngas alone.<\/p>\n\n\n\n

Nanofiber quality stayed uniformly high across all catalyst compositions. Electron microscopy revealed fibers 10\u00a0to 60 nm in diameter, and Raman spectroscopy, which probes the structural order of carbon materials, showed an\u00a0average purity of roughly 97% and crystallinity of about 86% relative to a commercial standard. Even when\u00a0ethylene entered the gas mix, quality did not suffer.<\/p>\n\n\n\n

To understand why alloy composition so tightly controls electrochemical behavior, the researchers tracked atomic-scale structural changes inside the catalysts during operation using synchrotron X-ray techniques at Brookhaven\u00a0National Laboratory. The decisive factor was palladium hydride formation. Under sufficiently negative voltages,\u00a0hydrogen atoms penetrate the palladium lattice, creating a hydride phase that weakens CO binding and allows it\u00a0to desorb as a product.<\/p>\n\n\n\n

In palladium-rich alloys this transformation occurred rapidly. In Pd\u2080.\u2084Cu\u2080.\u2086 it proceeded gradually. In Pd\u2080.\u2081Cu\u2080.\u2089 it did\u00a0not occur at all. Copper dilutes palladium’s hydrogen affinity and suppresses the phase transition.<\/p>\n\n\n\n

Quantum mechanical calculations reinforced this picture. A computed phase diagram showed the voltage\u00a0threshold for hydride formation shifting steadily more negative as copper content rose. Surface science\u00a0experiments on model palladium crystals added mechanistic detail: depositing copper onto a palladium hydride\u00a0surface weakened CO binding while raising the energy barrier for hydrogen release.<\/p>\n\n\n\n

Together, these results explain why palladium-copper alloys favor CO production over hydrogen evolution, and\u00a0why adjusting alloy composition precisely controls the balance between the two.<\/p>\n\n\n\n

Where most CO\u2082 conversion produces short-lived products, this tandem strategy yields a solid material with\u00a0decades of carbon storage potential. Tuning a single compositional variable, the palladium-to-copper ratio,\u00a0simultaneously controls hydride formation, syngas makeup, and nanofiber yield while cutting the need for\u00a0expensive platinum group metals. The unexpected contribution of ethylene as a carbon feedstock adds a further\u00a0optimization lever that future computational work may help clarify.<\/p>\n","protected":false},"excerpt":{"rendered":"

Most efforts to recycle CO\u2082 turn it into fuels or chemicals that release carbon back into the atmosphere within\u00a0months. A more permanent solution would convert it into a solid material that locks carbon away for decades.\u00a0Carbon\u00a0nanofibers\u00a0are one such material. These nanoscale carbon structures already find use as concrete\u00a0additives, battery components, and textile sensors, applications where […]<\/p>\n","protected":false},"author":59,"featured_media":174831,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","nova_meta_subtitle":"The ratio of palladium to copper in an electrocatalyst governs syngas composition from CO2, shaping downstream carbon nanofiber growth for permanent carbon storage","footnotes":""},"categories":[5571],"tags":[10744,25388,12330,20596,10630,12270,10743],"supplier":[27685,27686],"class_list":["post-174797","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-co2-based","tag-carboncapture","tag-carbonnanotubes","tag-ccu","tag-electrocatalysis","tag-hydrogen","tag-nanofibers","tag-useco2","supplier-brookhaven-national-laboratory-2","supplier-royal-society-of-chemistry-2"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/174797","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=174797"}],"version-history":[{"count":3,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/174797\/revisions"}],"predecessor-version":[{"id":174844,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/174797\/revisions\/174844"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/174831"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=174797"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=174797"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=174797"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=174797"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}