Electrochemical CO 2 reduction (CO 2 R) is a sustainable way of producing carbon-neutral fuels, yet the efficiency is limited by its sluggish kinetics and complex reaction pathways. Developing active, selective, and stable CO 2 R electrocatalysts is challenging and entails intelligent material structure design and tailoring. Here we show a graphdiyne/graphene (GDY/ G) heterostructure as a 2D conductive scaffold to anchor monodispersed cobalt phthalocyanine (CoPc) and reduce CO 2 with an appreciable activity, selectivity, and durability. Advanced characterizations, e.g., synchrotron-based X-ray absorption spectroscopy (XAS), and density functional theory (DFT) calculation disclose that the strong electronic coupling between GDY and CoPc, together with the high surface area, abundant reactive centers, and electron conductivity provided by graphene, synergistically contribute to this distinguished electrocatalytic performance. Electrochemical measurements revealed a high FE CO of 96% at a partial current density of 12 mA cm −2 in a H-cell and an FE CO of 97% at 100 mA cm −2 in a liquid flow cell, along with a durability over 24 h. The per-site turnover frequency of CoPc reaches 37 s −1 at −1.0 V vs RHE, outperforming most of the reported phthalocyanine-and porphyrin-based electrocatalysts. The usage of the GDY/G heterostructure as a scaffold can be further extended to other organometallic complexes beyond CoPc. Our findings lend credence to the prospect of the GDY/G hybrid contributing to the design of single-molecule dispersed CO 2 R catalysts for sustainable energy conversion.

Strong catalyst−support interaction plays a key role in heterogeneous catalysis, as has been well-documented in high-temperature gas-phase chemistry, such as the water gas shift reaction. Insight into how catalyst−support interactions can be exploited to optimize the catalytic activity in aqueous electrochemistry, however, is still lacking. In this work, we show the rationally designed electrocatalyst/support interface can greatly impact the overall electrocatalytic activity of Ni−Fe layered double hydroxide (NiFeLDH) in water oxidation. In particular, the use of Co as a non-noble metal support greatly improves the activity of NiFeLDH 10-fold compared to the traditional electrocatalytic supports such as fluorine-/ indium-doped tin oxide (FTO/ITO) and glassy carbon. We attribute the activity enhancement of NiFeLDH/Co to the in situ formation of a porous NiFeCoO x H y layer via Co incorporation, which dramatically promotes the redox chemistry of metal centers on the outer surface and enhances the electrical conductivity of the catalyst over 2 orders of magnitude. This new discovery highlights the importance of a rationally designed electrocatalyst/support interface and offers a new paradigm for designing and developing highly active electrocatalytic systems via marrying catalyst and support and creating synergy.

Electrochemical CO 2 conversion is a promising way for sustainable chemical fuel production, yet the conversion efficiency is strongly limited by the sluggish kinetics and complex reaction pathways. Here we report the ultrathin conjugated metalloporphyrin covalent organic framework epitaxially grown on graphene as a two-dimensional van der Waals heterostructure to catalyze CO 2 reduction. Operando X-ray absorption and density functional theory calculations reveal the strong interlayer coupling leads to electron-deficient metal centers and speeds up electrocatalysis. The Co(III)-N 4 centers exhibit a CO Faradaic efficiency of 97% at a partial current density of 8.2 mA cm −2 in an H-cell, along with a stable running over 30 h. The selectivity of CO approached 99% with a partial current density of 191 mA cm −2 in a liquid flow cell, and the turnover frequency achieved 50 400 h −1 at −1.15 V vs RHE, outperforming most reported organometallic frameworks. This work highlights the key role of strong electronic coupling between van der Waals layers for accelerating the dynamics of CO 2 conversion.

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