Thermocleavable Cobalt Phthalocyanine Precursors for Electrode-Immobilized Catalysts in CO2-to-Methanol Conversion

Abstract Molecule-electrode hybrid materials based on cobalt phthalocyanine (CoPc) supported on carbon nanostructures have emerged as highly effective electrocatalysts for the selective six-electron reduction of CO2 to methanol (e-methanol). However, the strong π-stacking tendency of CoPc leads to poor solubility and hinders its uniform integration with conductive supports such as multiwalled carbon nanotubes (CNTs), limiting the controlled preparation of well-defined hybrid architectures. Here, we introduce a thermocleavable CoPc-ester precursor strategy that enables the synthesis of a highly dispersed CoPc-acid@CNT hybrid catalyst. Controlled thermal activation cleaves the solubilizing ester groups, generating insoluble CoPc-acid species that molecularly anchor onto the CNT surface. This approach promotes active site dispersion, as supported by electron microscopy, and alters the local environment of the Co-bound *CO intermediate, as indicated by a different Stark tuning response in operando IR spectroscopy relative to conventionally prepared CoPc@CNT materials. Under H-cell conditions, the optimized hybrid catalyst achieves a methanol Faradaic efficiency (FE) of 44.4 ± 0.8% at a total current density of 18.9 mA/cm2, compared with 39.8 ± 2.6% at 27.1 mA/cm2 for the benchmark CoPc@CNT system tested under the same conditions (mean ± standard deviation, n = 3), a modest difference of borderline statistical significance. To place these results in a broader process context, we also present a prospective techno-economic analysis (TEA) and life-cycle analysis (LCA) that combine experimentally measured product distributions and cell voltage with literature-based flow cell assumptions. The baseline TEA gives a minimum selling price of $4.16/kg for e-methanol, while a modeled target of $0.41/kg requires simultaneous improvements in current density, methanol FE, electricity cost, CO2 conversion, electrolyzer capital cost and cell voltage beyond those demonstrated in the present H-cell system. The baseline LCA indicates a 34% reduction in carbon intensity (CI) relative to fossil-derived methanol, while near-zero CI requires high methanol FE together with renewable heat integration for methanol distillation. Collectively, these results identify thermocleavable molecular precursors as a useful strategy for controlling molecular catalyst dispersion and anchoring on conductive carbon supports, while also showing that high current density operation, catalyst layer optimization and long-term durability remain important targets for future development.