Electrochemical reduction of CO2 (CO2RR) provides an attractive pathway to achieve a carbon-neutral energy cycle. Single-atom catalysts (SAC) have shown unique potential in heterogeneous catalysis, but their structural simplicity prevents them from breaking linear scaling relationships. In this study, we develop a feasible strategy to precisely construct a series of electrocatalysts featuring well-defined single-atom and dual-site iron anchored on nitrogen-doped carbon matrix (Fe1–N–C and Fe2–N–C). The Fe2–N–C dual-atom electrocatalyst (DAC) achieves enhanced CO Faradaic efficiency above 80% in wider applied potential ranges along with higher turnover frequency (26,637 h–1) and better durability compared to SAC counterparts. Furthermore, based on in-depth experimental and theoretical analysis, the orbital coupling between the iron dual sites decreases the energy gap between antibonding and bonding states in *CO adsorption. This research presents new insights into the structure–performance relationship on CO2RR electrocatalysts at the atomic scale and extends the application of DACs for heterogeneous electrocatalysis and beyond.

The rational design of previously unidentified materials that could realize excellent electrochemical-controlled optical and charge storage properties simultaneously, are especially desirable and useful for fabricating smart multifunctional devices. Here, a facile synthesis of a 1D-d conjugated coordination polymer (Ni-BTA) is reported, consisting of metal (Ni)-containing nodes and organic linkers (1,2,4,5-benzenetetramine), which could be easily grown on various substrates via a scalable chemical bath deposition method. The resulting Ni-BTA film exhibits superior performances for both electrochromic and energy storage functions, such as large optical modulation (61.3%), high coloration efficiency (223.6 cm 2 C −1), and high gravimetric capacity (168.1 mAh g −1). In particular, the Ni-BTA film can maintain its electrochemical recharge-ability and electrochromic properties even after 10 000 electrochemical cycles demonstrating excellent durability. Moreover, a smart energy storage indicator is demonstrated in which the energy storage states can be visually recognized in real time. The excellent electrochromic and charge storage performances of Ni-BTA films present a great promise for Ni-BTA nanowires to be used as practical electrode materials in various applications such as electrochromic devices, energy storage cells, and multifunctional smart windows.

Multi‐metal oxide (MMO) materials have significant potential to facilitate various demanding reactions by providing additional degrees of freedom in catalyst design. However, a fundamental understanding of the (electro)catalytic activity of MMOs is limited because of the intrinsic complexity of their multi‐element nature. Additional complexities arise when MMO catalysts have crystalline structures with two different metal site occupancies, such as the spinel structure, which makes it more challenging to investigate the origin of the (electro)catalytic activity of MMOs. Here, uniform‐sized multi‐metal spinel oxide nanoparticles composed of Mn, Co, and Fe as model MMO electrocatalysts are synthesized and the contributions of each element to the structural flexibility of the spinel oxides are systematically studied, which boosts the electrocatalytic oxygen reduction reaction (ORR) activity. Detailed crystal and electronic structure characterizations combined with electrochemical and computational studies reveal that the incorporation of Co not only increases the preferential octahedral site occupancy, but also modifies the electronic state of the ORR‐active Mn site to enhance the intrinsic ORR activity. As a result, nanoparticles of the optimized catalyst, Co0.25Mn0.75Fe2.0‐MMO, exhibit a half‐wave potential of 0.904 V (versus RHE) and mass activity of 46.9 A goxide−1 (at 0.9 V versus RHE) with promising stability.

Rational control of the coordination environment of atomically dispersed catalysts is pivotal to achieve desirable catalytic reactivity. We report the reversible control of coordination structure in atomically dispersed electrocatalysts via ligand exchange reactions to reversibly modulate their reactivity for oxygen reduction reaction (ORR). The CO‐ligated atomically dispersed Rh catalyst exhibited ca. 30‐fold higher ORR activity than the NHx‐ligated catalyst, whereas the latter showed three times higher H2O2 selectivity than the former. Post‐treatments of the catalysts with CO or NH3 allowed the reversible exchange of CO and NHx ligands, which reversibly tuned oxidation state of metal centers and their ORR activity and selectivity. DFT calculations revealed that more reduced oxidation state of CO‐ligated Rh site could further stabilize the *OOH intermediate, facilitating the two‐ and four‐electron pathway ORR. The reversible ligand exchange reactions were generalized to Ir‐ and Pt‐based catalysts.

Single-atom M-N-C catalysts have attracted tremendous attention for their application to electrocatalysis. Nitrogen-coordinated mononuclear metal moieties (MN x moities) are bio-inspired active sites that are analogous to various metal-porphyrin cofactors. Given that the functions of metal-porphyrin cofactors are highly dependent on the local coordination environments around the mononuclear active site, engineering MN x active sites in heterogeneous M-N-C catalysts would provide an additional degree of freedom for boosting their electrocatalytic activity. This work presents a local coordination structure modification of FeN 4 moieties via morphological engineering of graphene support. Introducing highly wrinkled structure in graphene matrix induces nonplanar distortion of FeN 4 moieties, resulting in the modification of electronic structure of mononuclear Fe. Electrochemical analysis combined with firstprinciples calculations reveal that enhanced electrocatalytic lithium polysulfide conversion, especially the Li 2 S redox step, is attributed to the local structure modified FeN 4 active sites, while increased specific surface area also contributes to improved performance at low C-rates. Owing to the synergistic combination of atomic-level modified FeN 4 active sites and morphological advantage of graphene support, Fe-N-C catalysts with wrinkled graphene morphology show superior lithium-sulfur battery performance at both low and high C-rates (particularly 915.9 mAh g −1 at 5 C) with promising cycling stability.