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  "slug": "selectivity-control-catalysis",
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  "angle": "Three ChemRxiv preprints offer new levers on selectivity: a control principle, a light-assisted alloy, and dilute-CO2 C2 synthesis.",
  "headline": "The selectivity problem: three new levers for making chemistry choose",
  "dek": "A validated 'turnover-frequency control' principle for endergonic reactions, a CuPt single-atom alloy that splits propane aromatization across two metals under light, and a finding that dilute CO2 beats pure CO2 for C2 products — all in ChemRxiv preprints this week.",
  "published_at": "2026-10-15T01:10:31Z",
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    "trust_text": "Reported · 3 sources",
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    {
      "text": "A new principle, 'turnover-frequency control,' is proposed as governing selectivity in endergonic reactions; it was experimentally validated in a fuel-driven Diels-Alder reaction where modulating carbodiimide hydration fueling inverted the product distribution.",
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      "text": "Silica-supported CuPt single-atom alloys decouple propane dehydroaromatization: Pt sites handle C-H activation while the Cu host promotes visible light-assisted C-C coupling of C3 intermediates, enabling a parallel aromatization pathway to benzene.",
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      "text": "Dilute CO2 streams (5-33% v/v) can yield higher C2 selectivity than pure CO2 on copper-based electrocatalysts — the 'CO2 concentration inversion effect' — with *CO production rate and *CO C-C coupling efficiency as the two kinetic descriptors.",
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  "sections": [
    {
      "heading": "Why selectivity is the hard part",
      "paragraphs": [
        {
          "markdown": "Making molecules react is easy; making them react the way you want is chemistry's oldest hard problem. The traditional answers come in two flavors — thermodynamic control, where the most stable product wins, and kinetic control, where the fastest reaction wins. Three ChemRxiv preprints posted October 14 each offer a different, newer answer, and the common thread is selectivity: the product distribution, not just the reaction rate.",
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    {
      "heading": "A third kind of control",
      "paragraphs": [
        {
          "markdown": "Li, Ragazzon and colleagues report what they call 'turnover-frequency control' as the governing principle for selectivity in endergonic — energy-uphill — reactions. Unlike thermodynamic or kinetic control, this mechanism adjusts the kinetic barrier diagram to manipulate product distributions in non-equilibrium systems.",
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          "markdown": "They validated it experimentally in a fuel-driven Diels-Alder reaction involving furan derivatives and maleic acid: by modulating carbodiimide hydration fueling, they inverted the product distribution, and the model predicted non-monotonic responses to fueling rate. External fueling, in other words, becomes a dial for which product forms.",
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        },
        {
          "markdown": "The authors pitch the framework for designing complex non-equilibrium chemical networks, with advanced synthetic chemistry and autonomous chemical manufacturing as the applications. One caveat is on the record already: the paper's brief notes that no open-source code or dataset was provided for the analytical model, so independent testing starts from the paper alone.",
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    },
    {
      "heading": "Splitting the job across two metals, with light",
      "paragraphs": [
        {
          "markdown": "Wang, Kar, Swearer and colleagues take a materials route to selectivity in propane dehydroaromatization — upgrading propane toward benzene. Their catalyst is a silica-supported CuPt single-atom alloy, and the trick is division of labor: platinum sites are responsible for propane dehydrogenation, while the copper host promotes visible light-assisted C-C coupling of C3 intermediates.",
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          "markdown": "The Cu-Pt interface also promotes cyclization, enabling a parallel aromatization pathway to benzene. The paper frames this as a design principle — light-assisted single-atom/host cooperation — for plasmonic alkane upgrading.",
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        },
        {
          "markdown": "The open items are the industrial ones: the brief lists long-term catalyst stability under industrial conditions and scalability of the silica-supported synthesis as not yet shown. Selectivity in the lab and selectivity in a reactor are different achievements.",
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    {
      "heading": "Less CO2, more C2",
      "paragraphs": [
        {
          "markdown": "Yu and colleagues report the most counterintuitive result of the three. In copper-based electrocatalysis, dilute CO2 streams — 5 to 33% by volume — can achieve higher selectivity for C2 products than pure CO2, a phenomenon the authors term the 'CO2 concentration inversion effect.'",
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        {
          "markdown": "That challenges the conventional requirement for high-purity CO2 in C2+ electrosynthesis, which matters because purifying CO2 is expensive. To make the effect predictable, the team introduced two kinetic descriptors — the *CO production rate and the *CO C-C coupling efficiency — arguing that C2 formation is governed by a catalyst-tunable balance between *CO supply and coupling kinetics, validated with in-situ FT-IR spectroscopy.",
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        {
          "markdown": "The effect is demonstrated for specific copper catalyst families named in the paper — B-doped Cu, Ag@Cu2O, and Cu2(OH)2CO3-derived Cu — so the next question is how broadly the inversion generalizes across catalyst chemistries and operating conditions.",
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    {
      "heading": "What to watch",
      "paragraphs": [
        {
          "markdown": "Three levers, one theme: selectivity as something you engineer rather than inherit. The turnover-frequency principle wants independent replication with the model in hand; the CuPt alloy wants a stability test; the CO2 inversion wants a broader catalyst survey. Each is a preprint, so each is an opening bid — the interesting part is what the follow-up measurements say.",
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  "unresolved": [
    "Independent validation of the turnover-frequency control model (no open code or dataset provided)",
    "Long-term stability and scalability of the CuPt single-atom alloy under industrial conditions",
    "How broadly the CO2 concentration inversion effect generalizes beyond the reported copper catalyst families"
  ],
  "decision_card": {
    "useful_for": [
      "Catalysis researchers and process chemists",
      "Carbon-utilization and CO2-electroreduction watchers",
      "Teams working on non-equilibrium chemical systems"
    ],
    "not_for": [
      "Anyone needing peer-reviewed, scaled process data"
    ],
    "compare_against": [
      "Thermodynamic and kinetic control baselines",
      "Conventional propane aromatization catalysts",
      "Pure-CO2 electroreduction benchmarks"
    ]
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      "title": "An experimentally-validated principle for selectivity in endergonic reactions",
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      "source_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010447/v1",
      "published_date": "2026-10-14"
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      "title": "Light-assisted bifunctionality in CuPt single-atom alloys for propane dehydroaromatization",
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      "title": "The CO₂ Concentration Inversion Effect: *CO Generation Rate and *CO C-C Coupling Efficiency as Dual Kinetic Descriptors for Catalyst-Dependent C₂ Selectivity in Dilute CO₂ Electroreduction¹",
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