Unlocking the Potential for Methanol Synthesis via Electrochemical CO2 Reduction Using CoPc-Based Molecular Catalysts.

The electrochemical CO2 reduction reaction (CO2RR) to produce methanol (CH3OH) is an attractive yet challenging approach due to a lack of selective electrocatalysts. An immobilized cobalt phthalocyanine (CoPc) molecular catalyst has emerged as a promising electrocatalyst for CH3OH synthesis, demonstrating decent activity and selectivity through a CO2-CO-CH3OH cascade reaction. However, CoPc's performance is limited by its weak binding strength toward the CO intermediate. Recent advancements in molecular modification aimed at enhancing CO intermediate binding have shown great promise in improving CO2-to-CH3OH performance. In this Perspective, we discuss the competitive binding mechanism between CO2 and CO that hinders CH3OH formation and summarize effective molecular modification strategies that can enhance both the binding of the CO intermediate and the conversion of the CO2-to-CH3OH activity. Finally, we offer future perspectives on optimization strategies to inspire further research efforts to fully unlock the potential for methanol synthesis via the CO2RR using molecular catalysts.

Tetracationic Cobalt 3,4-pyridinoporphyrazine for Direct CO2 to Methanol Conversion Escaping the CO Intermediate Pathway.

Molecular catalysts offer a unique opportunity to implement different chemical functionalities to steer the efficiency and selectivity for the CO2 reduction for instance. Metalloporphyrins and metallophthalocyanines are under high scrutiny since their most classic derivatives the tetraphenylporphyrin (TPP) and parent phthalocyanine (Pc), have been used as the molecular platform to install, hydrogen bonds donnors, proton relays, cationic fragments, incorporation in MOFs and COFs, to enhance the catalytic power of these catalysts. Herein, we examine the electrocatalytic properties of the tetramethyl cobalt (II) tetrapyridinoporphyrazine (CoTmTPyPz) for the reduction of CO2 in heterogeneous medium when adsorbed on carbon nanotubes (CNT) at a carbon paper (CP) electrode. Unlike reported electrocatalysis with cobalt based phthalocyanine where CO was advocated as the two electron and two protons reduced intermediate on the way to the formation of methanol, we found here that CoTmTPyPz does not reduce CO to methanol. Henceforth, ruling out a mechanistic pathway where CO is a reaction intermediate.

Built-in electric field mediated S-scheme charge migration and Co-N4(II) sites in cobalt phthalocyanine/MIL-68(In)-NH2 heterojunction for boosting photocatalytic nitric oxide oxidation.

The efficiency of photocatalytic Nitric Oxide(NO) oxidation is limited by the lack of oxygen(O2) active sites and poor charge carrier separation. To address this challenge, we developed a molecular Cobalt Phthalocyanine modified MIL-68(In)-NH2 photocatalyst with a robust Built-in electric field(BIEF). In the 2 % CoPc-MIN sample, the BIEF strength is increased by 3.54 times and 5.83 times compared to pristine CoPc and MIL-68(In)-NH2, respectively. This BIEF facilitates the efficient S-scheme charge transfer, thereby enhancing photogenerated carrier separation. Additionally, the Co-N4(II) sites in CoPc can effectively trap the separated photoexcited electrons in the S-scheme system. In addition, the Co-N4(II) sites can also serve as active sites for O2 adsorption and activation, promoting the generation of superoxide radical (O2-), thereby driving the direct conversion of NO to nitrate(NO3-). Consequently, the 2 % CoPc-MIN sample exhibits a remarkable photocatalytic NO removal efficiency of 79.37 % while effectively suppressing the formation of harmful by-product nitrogen dioxide(NO2) to below 3.5 ppb. This study provides a feasible strategy for designing high-efficiency O2 activation photocatalysts for NO oxidation.

Electrochemical Synthesis of Urea: Co-Reduction of Nitrite and Carbon Dioxide on Binuclear Cobalt Phthalocyanine.

Exploration of molecular catalysts with the atomic-level tunability of molecular structures offers promising avenues for developing high-performance catalysts for the electrochemical co-reduction reaction of carbon dioxide (CO2) and nitrite (NO2 -) into value-added urea. In this work, a binuclear cobalt phthalocyanine (biCoPc) catalyst is prepared through chemical synthesis and applied as a C─N coupling catalyst toward urea. Achieving a remarkable Faradaic efficiency of 47.4% for urea production at -0.5 V versus reversible hydrogen electrode (RHE), this biCoPc outperforms many known molecular catalysts in this specific application. Its unique planar macromolecular structure and the increased valence state of cobalt promote the adsorption of nitrogenous and carbonaceous species, a critical factor in facilitating the multi-electron C─N coupling. Combining highly sensitive in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) with density functional theory (DFT) calculations, the linear adsorbed CO (COL) and bridge adsorbed CO (COB) is captured on biCoPc catalyst during the co-reduction reaction. COB, a pivotal intermediate in the co-reduction from CO2 and nitrite to urea, is evidenced to be labile and may be attacked by nitrite, promoting urea production. This work demonstrates the importance of designing molecular catalysts for efficient co-reduction of CO2 and nitrite to urea.

Covalent Functionalization of Silicon with Plasma-Grown "Fuzzy" Graphene: Robust Aqueous Photoelectrodes for CO2 Reduction by Molecular Catalysts.

Carbon electrodes are ideal for electrochemistry with molecular catalysts, exhibiting facile charge transfer and good stability. Yet for solar-driven catalysis with semiconductor light absorbers, stable semiconductor/carbon interfaces can be difficult to achieve, and carbon's high optical extinction means it can only be used in ultrathin layers. Here, we demonstrate a plasma-enhanced chemical vapor deposition process that achieves well-controlled deposition of out-of-plane "fuzzy" graphene (FG) on thermally oxidized Si substrates. The resulting Si|FG interfaces possess a silicon oxycarbide (SiOC) interfacial layer, implying covalent bonding between Si and the FG film that is consistent with the mechanical robustness observed from the films. The FG layer is uniform and tunable in thickness and optical transparency by deposition time. Using p-type Si|FG substrates, noncovalent immobilization of cobalt phthalocyanine (CoPc) molecular catalysts was employed for the photoelectrochemical reduction of CO2 in aqueous solution. The Si|FG|CoPc photocathodes exhibited good catalytic activity, yielding a current density of ∼1 mA/cm2, Faradaic efficiency for CO of ∼70% (balance H2), and stable photocurrent for at least 30 h at -1.5 V vs Ag/AgCl under 1-sun illumination. The results suggest that plasma-deposited FG is a robust carbon electrode for molecular catalysts and suitable for further development of aqueous-stable Si photocathodes for CO2 reduction.

Mitigating Cobalt Phthalocyanine Aggregation in Electrocatalyst Films through Codeposition with an Axially Coordinating Polymer.

Cobalt phthalocyanine (CoPc) is a promising molecular catalyst for aqueous electroreduction of CO2, but its catalytic activity is limited by aggregation at high loadings. Codeposition of CoPc onto electrode surfaces with the coordinating polymer poly(4-vinylpyridine) (P4VP) mitigates aggregation in addition to providing other catalytic enhancements. Transmission and diffuse reflectance UV-vis measurements demonstrate that a combination of axial coordination and π-stacking effects from pyridyl moieties in P4VP serve to disperse cobalt phthalocyanine in deposition solutions and help prevent reaggregation in deposited films. Polymers lacking axial coordination, such as Nafion, are significantly less effective at cobalt phthalocyanine dispersion in both the deposition solution and in the deposited films. SEM images corroborate these findings through particle counts and morphological analysis. Electrochemical measurements show that CoPc codeposited with P4VPonto carbon electrode surfaces reduces CO2 with higher activity and selectivity compared to the catalyst codeposited with Nafion.

Cobalt Phthalocyanine-Modified Magnetic Metal-Organic Frameworks for Specific Enrichment of Phosphopeptides.

For mass spectrometry (MS)-based phosphoproteomics studies, sample pretreatment is an essential step for efficient identification of low-abundance phosphopeptides. Herein, a cobalt phthalocyanine-modified magnetic metal-organic framework (MOF) (Fe3O4@MIL-101-CoPc) was prepared and applied to enrich phosphopeptides before MS analysis. Fe3O4@MIL-101-CoPc exhibited an excellent magnetic response (74.98 emu g-1) and good hydrophilicity (7.75°), which were favorable for the enrichment. Fe3O4@MIL-101-CoPc showed good enrichment performance with high selectivity (1:1:5000), sensitivity (0.1 fmol), reusability (10 circles), and recovery (91.3%). Additionally, the Fe3O4@MIL-101-CoPc-based MS method was able to successfully detect 827 phosphopeptides from the A549 cell lysate, demonstrating a high enrichment efficiency (89.3%). This study promotes the application of postfunctionalized MOFs for phosphoproteomics analysis.

Linker Mediated Electronic-State Manipulation of Conjugated Organic Polymers Enabling Highly Efficient Oxygen Reduction.

Conjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure-performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc-CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc-CPs) are judiciously crafted via in situ assembling square-planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde-based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5-thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene-2,5-dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc-CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron-withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d-orbital electrons, thereby downshifting the Co d-band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR-relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular-level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.

Tailored Local Electronic Environment of Co-N4 Sites in Cobalt Phthalocyanines for Enhanced CO2 Reduction Reaction.

Atomically dispersed Co-N4-based catalysts have been recently emerging as one of the most promising candidates for facilitating CO2 reduction reaction (CO2RR). The local electronic environment of Co-N4 sites in these catalysts is considered to play a critical role in adjusting the catalytic performance, the effort of which however is not yet clearly verified. Herein, a series of cobalt phthalocyanines with different peripheral substituents including unsubstituted phthalocyanine Co(II) (CoPc), 2,9,16,23-tetramethoxyphthalocyaninato Co(II) (CoPc-4OCH3), and 2,9,16,23-tetranitrophthalocyaninato Co(II) (CoPc-4NO2) are supported onto the surface of the multi-walled carbon nanotubes (CNTs), affording CoPc@CNTs, CoPc-4OCH3@CNTs, and CoPc-4NO2@CNTs. X-ray photoelectron spectroscopy and X-ray absorption near-edge structure measurements disclose the influence of the peripheral substituents on the local electronic structure of Co atoms in these three catalysts. Electrochemical tests indicate the higher CO2RR performance of CoPc-4OCH3@CNTs compared to CoPc@CNTs and CoPc-4NO2@CNTs as exemplified by the higher Faraday efficiency of CO, larger part current densities, and better stability displayed by CoPc-4OCH3@CNTs at the applied voltage range from -0.6 to -1.0 V versus RHE in both H-cell and flow cell. These results highlight the effect of the electron-donating -OCH3 substituent on the enhanced catalytic activity of CoPc-4OCH3@CNTs, which will help develop Co-N4-based catalysts with promising catalytic performance toward CO2RR.

Directed Electron Delivery from a Pb-Free Halide Perovskite to a Co(II) Molecular Catalyst Boosts CO2 Photoreduction Coupled with Water Oxidation.

The development of high-performance photocatalytic systems for CO2 reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb-free halide perovskite Cs2AgBiBr6 nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 µmol g-1 h-1 for visible-light-driven CO2-to-CO conversion coupled with water oxidation to O2, over 8 times of the unmodified Cs2AgBiBr6 (36±8 µmol g-1 h-1), also far surpassing the documented systems (<150 µmol g-1 h-1). Besides the improved intrinsic activity, electrochemical, computational, ex-/in situ X-ray photoelectron and X-ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs2AgBiBr6 can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis.

Effects of the Carbon Support on Heterogeneous Molecular Catalysts for Carbon Dioxide Reduction.

Molecular catalysts stabilized on a support material, also called heterogeneous molecular catalysts, exhibit excellent performance in carbon dioxide reduction reaction (CO2 RR). Different support in these electrocatalysts can have a substantial influence on the activity, making support control one tool to enhance the CO2 RR performance. However, a systematic understanding of the support effects is lacking. Taking cobalt phthalocyanine (CoPc) immobilized onto different carbon materials as examples, we demonstrate that the surface area, pore structure and the morphology of the as-prepared heterogeneous molecular catalysts can influence the CO2 transfer and adsorption, and then change the CO2 RR activity. In contrast to the other four materials, CoPc/mesoporous carbon (MC) can efficiently convert carbon dioxide to carbon monoxide at minimal overpotential (-0.8 V vs. RHE) due to its special nanostructure and pore distribution. The results of this study suggest that the performance of electrocatalytic reduction of carbon dioxide can be improved by changing different substrates.

Ultrathin, Cationic Covalent Organic Nanosheets for Enhanced CO2 Electroreduction to Methanol.

Metalloporphyrins and metallophthalocyanines emerge as popular building blocks to develop covalent organic nanosheets (CONs) for CO2 reduction reaction (CO2 RR). However, existing CONs predominantly yield CO, posing a challenge in achieving efficient methanol production through multielectron reduction. Here, ultrathin, cationic, and cobalt-phthalocyanine-based CONs (iminium-CONs) are reported for electrochemical CO2 -to-CH3 OH conversion. The integration of quaternary iminium groups enables the formation of ultrathin morphology with uniformly anchored cobalt active sites, which are pivotal for facilitating rapid multielectron transfer. Moreover, the cationic iminium-CONs exhibit a lower activity for hydrogen evolution side reaction. Consequently, iminium-CONs manifest significantly enhanced selectivity for methanol production, as evidenced by a remarkable 711% and 270% improvement in methanol partial current density (jCH3OH ) compared to pristine CoTAPc and neutral imine-CONs, respectively. Under optimized conditions, iminium-CONs deliver a high jCH3OH of 91.7 mA cm-2 at -0.78 V in a flow cell. Further, iminium-CONs achieve a global methanol Faradaic efficiency (FECH3OH ) of 54% in a tandem device. Thanks to the single-site feature, the methanol is produced without the concurrent generation of other liquid byproducts. This work underscores the potential of cationic covalent organic nanosheets as a compelling platform for electrochemical six-electron reduction of CO2 to methanol.

Langmuir-Blodgett Monolayer of Cobalt Phthalocyanine as Ultralow Loading Single-Atom Catalyst for Highly Efficient H2O2 Production.

The electrochemical production of H2O2 via the two-electron oxygen-reduction reaction (2e- ORR) has been actively studied using systems with atomically dispersed metal-nitrogen-carbon (M-N-C) structures. However, the development of well-defined M-N-C structures that restrict the migration and agglomeration of single-metal sites remains elusive. Herein, we demonstrate a Langmuir-Blodgett (LB) monolayer of cobalt phthalocyanine (CoPc) on monolayer graphene (LB CoPc/G) as a single-metal catalyst for the 2e- ORR. The as-prepared CoPc LB monolayer has a ß-form crystalline structure with a lattice space for the facile adsorption of oxygen molecules on the cobalt active sites. The CoPc LB monolayer system provides highly exposed Co atoms in a well-defined structure without agglomeration, resulting in significantly improved catalytic activity, which is manifested by a very high H2O2 production rate per catalyst (31.04 mol gcat-1 h-1) and TOF (36.5 s-1) with constant production stability for 24 hours. To the best of our knowledge, the CoPc LB monolayer system exhibits the highest H2O2 production rate per active site. This fundamental study suggests that an LB monolayer of molecules with single-metal atoms as a well-defined structure works for single-atom catalysts.

Amphiphilic Cobalt Phthalocyanine Boosts Carbon Dioxide Reduction.

Due to the easy accessibility, chemical stability, and structural tunability of the macrocyclic skeleton, cobalt phthalocyanines immobilized on carbon supports offer an ideal research model for advanced electrochemical carbon dioxide reduction reaction (eCO2 RR). In this work, an amphiphilic cobalt phthalocyanine (TC-CoPc) is loaded on multiwalled carbon nanotubes to reveal the roles of hydrophilic/hydrophobic properties on catalytic efficiency. Surprisingly, the resultant electrode exhibits a CO Faradaic efficiency (FECO ) of 95% for CO2 RR with turnover frequency (TOF) of 29.4 s-1 at an overpotential of 0.585 V over long-term electrolysis in a H-type cell. In the membrane electrode assembly (MEA) device, the boosted transport of water vapor to the catalyst layer slows down carbonate crystallization and enhances the stability of the electrode, with FECO value of >99% over 27 h at -0.25 A, representing the best selectivity and stability among reported molecular catalysts in MEA devices. The amphiphilic cobalt phthalocyanine, which decreases interfacial charge and mass transfer resistance and maintains effective contact between active sites and the electrolyte, highlights the exceptional CO2 conversion from a molecular perspective.

Integration of Cobalt Phthalocyanine, Acetylene Black and Cu2 O Nanocubes for Efficient Electroreduction of CO2 to C2 H4.

Suppressing side reactions and simultaneously enriching key intermediates during CO2 reduction reaction (CO2 RR) has been a challenge. Here, we propose a tandem catalyst (Cu2 O NCs-C-Copc) consisting of acetylene black, cobalt phthalocyanine (Copc) and cuprous oxide nanocubes (Cu2 O NCs) for efficient CO2 -to-ethylene conversion. Density-functional theory (DFT) calculation combined with experimental verification demonstrated that Copc can provide abundant CO to nearby copper sites while acetylene black successfully reduces the formation energies of key intermediates, leading to enhanced C2 H4 selectivity. X-ray photoelectron spectroscopy (XPS) and potentiostatic tests indicated that the catalytic stability of Cu2 O NCs-C-Copc was significantly enhanced compared with Cu2 O NCs. Finally, the industrial application prospect of the catalyst was evaluated using gas diffusion electrolyzers. The F E C 2 H 4 ${{\rm { F}}{{\rm { E}}}_{{{\rm { C}}}_{{\rm { 2}}}{{\rm { H}}}_{{\rm { 4}}}}}$ of Cu2 O NCs-C-Copc can reach to 58.4 % at -1.1 V vs. RHE in 0.1 M KHCO3 and 70.3 % at -0.76 V vs. RHE in 1.0 M KOH. This study sheds new light on the design and development of highly efficient CO2 RR tandem catalytic systems.

Translating Catalyst-Polymer Composites from Liquid to Gas-Fed CO2 Electrolysis: A CoPc-P4VP Case Study.

The electrochemical CO2 reduction reaction (CO2RR) in gas-fed flow electrolyzers using gas diffusion electrodes (GDEs) generates industrially relevant activities and provides a promising approach for carbon recycling. Developing effective catalyst systems on GDEs is critical for achieving high activities. Catalyst-polymer composites (CPCs) formed between immobilized molecular catalysts and coordinating polymers exhibit positive synergies for the enhancement of CO2RR activity. However, previous studies of CPCs have been primarily confined to liquid reaction platforms, and there are few examples of translating CPCs to GDE architectures. This suggests a knowledge gap exists in translating between the two platforms. Herein, we identify and bridge that gap by demonstrating a case study for the (poly-4-vinylpyridine)-encapsulated cobalt phthalocyanine (CoPc-P4VP) CPC. We identify a major knolwedge gap in the overlooked factor of CPC's hydrophobicity, which plays a significant role in gas-fed CO2RR but is often neglected in fundamental studies conducted on the liquid reaction platform. We bridge this gap by correlating catalyst hydrophobicity in liquid CO2RR with activity in gas-fed CO2RR by means of water contact angle measurements. Our case study underscores the importance of incorporating an engineering perspective into CPC studies and the necessity to consider hydrophobicity in CPC design and evaluation. This approach will hopefully accelerate the applied studies of this group of promising catalytic materials in gas-fed CO2 electrolysis.

Schottky Junction Nanozyme Based on Mn-Bridged Co-Phthalocyanines and Ti3C2Tx Nanosheets Boosts Integrative Type I and II Photosensitization for Multimodal Cancer Therapy.

Cancer phototheranostics have the potential for significantly improving the therapeutic effectiveness, as it can accurately diagnose and treat cancer. However, the current phototheranostic platforms leave much to be desired and are often limited by tumor hypoxia. Herein, a Schottky junction nanozyme has been established between a manganese-bridged cobalt-phthalocyanines complex and Ti3C2Tx MXene nanosheets (CoPc-Mn/Ti3C2Tx), which can serve as an integrative type I and II photosensitizer for enhancing cancer therapeutic efficacy via a photoacoustic imaging-guided multimodal chemodynamic/photothermal/photodynamic therapy strategy under near-infrared (808 nm) light irradiation. The Schottky junction not only possessed a narrow-bandgap, enhanced electron-hole separation ability and exhibited a potent redox potential but also enabled improved H2O2 and O2 supplying performances in vitro. Accordingly, the AS1411 aptamer-immobilized CoPc-Mn/Ti3C2Tx nanozyme illustrated high accuracy and excellent anticancer efficiency through a multimodal therapy strategy in in vitro and in vivo experiments. This work presents a valuable method for designing and constructing a multifunctional nanocatalytic medicine platform for synergistic cancer therapy of solid tumors.

Co3O4 Supported on Graphene-like Carbon by One-Step Calcination of Cobalt Phthalocyanine for Efficient Oxygen Reduction Reaction under Alkaline Medium.

Exploiting cost-effective and durable non-platinum electrocatalysts for oxygen reduction reaction (ORR) is of great significance for the development of abundant renewable energy conversion and storage technologies. Herein, a series of Co3O4 supported on graphene-like carbon (Co3O4/C) samples were firstly effectively synthesized by one-step calcination of cobalt phthalocyanine and their electrocatalytic performances were measured for ORR under an alkaline medium. By systematically adjusting the calcination temperature of cobalt phthalocyanine, we found that the material pyrolyzed at 750 °C (Co3O4/C-750) shows the best ORR electrocatalytic performance (half-wave potentials of 0.77 V (vs. RHE) in 0.1 M KOH) among all the control samples. Moreover, it displays better stability and superior methanol tolerance than commercial 20% Pt/C. The further electrochemical test results reveal that the process is close in characteristics to the four-electron ORR process on Co3O4/C-750. In addition, Co3O4/C-750 applied in the zinc-air battery presents 1.34 V of open circuit potential. Based on all the characterizations, the enhanced electrocatalytic performances of Co3O4/C-750 composite should be ascribed to the synergistic effect between Co3O4 and the graphene-like carbon layer structure produced by pyrolysis of cobalt phthalocyanine, as well as its high specific surface area.

Isolation of Highly Reactive Cobalt Phthalocyanine via Electrochemical Activation for Enhanced CO2 Reduction Reaction.

Electrochemical CO2 -to-CO conversion offers an attractive and efficient route to recycle CO2 greenhouse gas. Molecular catalysts, like CoPc, are proved to be possible replacement for precious metal-based catalysts. These molecules, a combination of metal center and organic ligand molecule, may evolve into single atom structure for enhanced performance; besides, the manipulation of molecules' behavior also plays an important role in mechanism research. Here, in this work, the structure evolution of CoPc molecules is investigated via electrochemical-induced activation process. After numbers of cyclic voltammetry scanning, CoPc molecular crystals become cracked and crumbled, meanwhile the released CoPc molecules migrate to the conductive substrate. Atomic-scale HAADF-STEM proves the migration of CoPc molecules, which is the main reason for the enhancement in CO2 -to-CO performance. The as-activated CoPc exhibits a maximum FECO of 99% in an H-type cell and affords a long-term durability at 100 mA cm-2 for 29.3 h in a membrane electrode assembly reactor. Density-functional theory (DFT) calculation also demonstrates a favorable CO2 activation energy with such an activated CoPc structure. This work provides a different perspective for understanding molecular catalysts as well as a reliable and universal method for practical utilization.

Microstructure Design Strategy for Molecularly Dispersed Cobalt Phthalocyanine and Efficient Mass Transport in CO2 Electroreduction.

Cobalt phthalocyanine (CoPc) has attracted particular interest owing to its excellent activity during the electrochemical CO2 conversion to CO. However, the efficient utilization of CoPc at industrially relevant current densities is still a challenge owing to its nonconductive property, agglomeration, and unfavorable conductive substrate design. Here, a microstructure design strategy for dispersing CoPc molecules on a carbon substrate for efficient CO2 transport during CO2 electrolysis is proposed and demonstrated. The highly dispersed CoPc is loaded on a macroporous hollow nanocarbon sheet to act as the catalyst (CoPc/CS). The unique interconnected and macroporous structure of the carbon sheet forms a large specific surface area to anchor CoPc with high dispersion and simultaneously boosts the mass transport of reactants in the catalyst layer, significantly improving the electrochemical performance. By employing a zero-gap flow cell, the designed catalyst can mediate CO2 to CO with a high full-cell energy efficiency of 57% at 200 mA cm-2 .