Ru Species Supported on MOF‐Derived N‐Doped TiO2/C Hybrids as Efficient Electrocatalytic/Photocatalytic Hydrogen Evolution Reaction Catalysts

The development of efficient catalysts is of great importance for hydrogen evolution reaction (HER) of water splitting via electrocatalytic/photocatalytic processes to remediate the current severe environmental and energy problems. By aid of the stabilization effects of uncoordinated groups and inherent pore‐confinement of amine‐functionalized metal–organic frameworks (NH₂‐MIL‐125), two forms of Ru species including nanoparticles (NPs) and/or single atoms (SAs) can be firmly embedded in NH₂‐MIL‐125 derived N‐doped TiO₂/C support (N‐TC), and thus obtain two kinds of samples named Ru‐NPs/SAs@N‐TC and Ru‐SAs@N‐TC, respectively. In the synthetic process, the initial feeding amount of Ru³⁺ ions not only strongly determines the final size and dispersion states of Ru species but also the morphology and defective structures of N‐TC support. Impressively, Ru‐NPs/SAs@N‐TC exhibit superior catalytic activities to Ru‐SAs@N‐TC for either electrocatalytic or photocatalytic HER. This should be attributed to its larger specific surface area and benefiting from synergistic coupling of Ru NPs and Ru SAs. It is envisioned that the present work can provide a new avenue for development of high‐efficiency and multifunctional hybrid catalysts in sustainable energy conversion.     

Facile Synthesis of Manganese‐Oxide‐Containing Mesoporous Nitrogen‐Doped Carbon for Efficient Oxygen Reduction

Developing low‐cost non‐precious metal catalysts for high‐performance oxygen reduction reaction (ORR) is highly desirable. Here a facile, in situ template synthesis of a MnO‐containing mesoporous nitrogen‐doped carbon (m‐N‐C) nanocomposite and its high electrocatalytic activity for a four‐electron ORR in alkaline solution are reported. The synthesis of the MnO‐m‐N‐C nanocomposite involves one‐pot hydrothermal synthesis of Mn₃O₄@polyaniline core/shell nanoparticles from a mixture containing aniline, Mn(NO₃)₂, and KMnO₄, followed by heat treatment to produce N‐doped ultrathin graphitic carbon coated MnO hybrids and partial acid leaching of MnO. The as‐prepared MnO‐m‐N‐C composite catalyst exhibits high electrocatalytic activity and dominant four‐electron oxygen reduction pathway in 0.1 M KOH aqueous solution due to the synergetic effect between MnO and m‐N‐C. The pristine MnO shows little electrocatalytic activity and m‐N‐C alone exhibits a dominant two‐electron process for ORR. The MnO‐m‐N‐C composite catalyst also exhibits superior stability and methanol tolerance to a commercial Pt/C catalyst, making the composite a promising cathode catalyst for alkaline methanol fuel cell applications. The synergetic effect between MnO and N‐doped carbon described provides a new route to design advanced catalysts for energy conversion.     

Dendrimer‐Functionalized Iron Oxide Nanoparticles for Specific Targeting and Imaging of Cancer Cells

We demonstrated a unique approach that combines a layer‐by‐layer (LbL) self‐assembly method with dendrimer chemistry to functionalize Fe₃O₄ nanoparticles (NPs) for specific targeting and imaging of cancer cells. In this approach, positively charged Fe₃O₄ NPs (8.4 nm in diameter) synthesized by controlled co‐precipitation of Fe^II and Fe^III ions were modified with a bilayer composed of polystyrene sulfonate sodium salt and folic acid (FA)‐ and fluorescein isothiocyanate (FI)‐functionalized poly(amidoamine) dendrimers of generation 5 (G5.NH₂‐FI‐FA) through electrostatic LbL assembly, followed by an acetylation reaction to neutralize the remaining surface amine groups of G5 dendrimers. Combined flow cytometry, confocal microscopy, transmission electron microscopy, and magnetic resonance imaging studies show that Fe₃O₄/PSS/G5.NHAc‐FI‐FA NPs can specifically target cancer cells overexpressing FA receptors. The present approach to functionalizing Fe₃O₄ NPs opens a new avenue to fabricating various NPs for numerous biological sensing and therapeutic applications.     

Refining Energy Levels in ReS2 Nanosheets by Low‐Valent Transition‐Metal Doping for Dual‐Boosted Electrochemical Ammonia/Hydrogen Production

Electrocatalytic nitrogen reduction reaction (NRR) and hydrogen evolution reaction (HER) are intriguing approaches to nitrogen fixation and hydrogen production under ambient conditions, given the need to discover efficient and stable catalysts to light up the “green chemistry” future. However, bottlenecks are often found during N₂/H₂O activation, the very first step of NRR/HER, due to energetic electron injection from the surface of electrocatalysts. It is reported that the bottlenecks for both NRR and HER can be tackled by engineering the energy level via low‐valent transition‐metal doping, simultaneously, where rhenium disulfide (ReS₂) is employed as a model platform to prove the concept. The doped low‐valent transition‐metal domains (e.g., Fe, Co, Ni, Cu, Zn) in ReS₂ provide more active sites for N₂/H₂O chemisorption and electron transfer, not only weakening the N?N/O? H bonds for easier dissociation through proton coupling, but also elevating d‐band center toward the Fermi level with more electron energy for N₂/H₂O reduction. As a result, it is found that iron‐doped ReS₂ nanosheets wrapped nitrogen‐doped carbon nanofiber (Fe‐ReS₂@N‐CNF) catalyst exhibits superior electrochemical activity with eightfold higher ammonia production yield of 80.4 µg h^?1 mg^?1_cat., and lower onset overpotential of 146 mV and Tafel slope of 63 mV dec^?1, when comparing with the pristine ReS₂.     

NiCo Alloy Nanoparticles Decorated on N‐Doped Carbon Nanofibers as Highly Active and Durable Oxygen Electrocatalyst

The exploring of catalysts with high‐efficiency and low‐cost for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the key issues for many renewable energy systems including fuel cells, metal–air batteries, and water splitting. Despite several decades pursuing, bifunctional oxygen catalysts with high catalytic performance at low‐cost, especially the one that could be easily scaled up for mass production are still missing and highly desired. Herein, a hybrid catalyst with NiCo alloy nanoparticles decorated on N‐doped carbon nanofibers is synthesized by a facile electrospinning method and postcalcination treatment. The hybrid catalyst NiCo@N‐C 2 exhibits outstanding ORR and OER catalytic performances, which is even surprisingly superior to the commercial Pt/C and RuO₂ catalysts, respectively. The synergetic effects between alloy nanoparticles and the N‐doped carbon fiber are considered as the main contributions for the excellent catalytic activities, which include decreasing the intrinsic and charge transfer resistances, increasing C?C, graphitic‐N/pyridinic‐N contents in the hybrid catalyst. This work opens up a new way to fabricate high‐efficient, low‐cost oxygen catalysts with high production.     

Polyformamidine‐Derived Non‐Noble Metal Electrocatalysts for Efficient Oxygen Reduction Reaction

A facile approach for the template‐free synthesis of highly active non‐noble metal based oxygen reduction reaction (ORR) electrocatalysts is presented. Porous Fe?N?C/Fe/Fe₃C composite materials are obtained by pyrolysis of defined precursor mixtures of polyformamidine (PFA) and FeCl₃ as nitrogen‐rich carbon and iron sources, respectively. Selection of pyrolysis temperature (700–1100 °C) and FeCl₃ loading (5–30 wt%) yields materials with differing surface areas, porosity, graphitization degree, nitrogen and iron content, as well as ORR activity. While the ORR activity of Fe‐free materials is limited (i.e., synthesized from pure PFA), a huge increase in activity is observed for catalysts containing Fe, revealing the participation of the metal dopant in the construction of active electrocatalytic sites. Further activity improvement is achieved via acid‐leaching and repeated pyrolysis, a result which is attributed to the creation of new active sites located at the surface of the porous nitrogen‐doped carbon by dissolution of the Fe and Fe₃C nanophases. The best performing catalyst, which was synthesized with a low Fe loading (i.e., 5 wt%) and at a pyrolysis temperature of 900 °C, exhibits high activity, excellent H₂O selectivity, extended stability, in both basic and acidic media as well as a remarkable tolerance toward methanol.     

2D Dual‐Metal Zeolitic‐Imidazolate‐Framework‐(ZIF)‐Derived Bifunctional Air Electrodes with Ultrahigh Electrochemical Properties for Rechargeable Zinc–Air Batteries

Here first a 2D dual‐metal (Co/Zn) and leaf‐like zeolitic imidazolate framework (ZIF‐L)‐pyrolysis approach is reported for the low‐cost and facile preparation of Co nanoparticles encapsulated into nitrogen‐doped carbon nanotubes (Co‐N‐CNTs). Importantly, the reasonable Co/Zn molar ratio in the ZIF‐L is the key to the emergence of the encapsulated microstructure. Specifically, high‐dispersed cobalt nanoparticles are fully encapsulated in the tips of N‐CNTs, leading to the full formation of highly active Co–N–C moieties for oxygen reduction and evolution reactions (ORR and OER). As a result, the obtained Co‐N‐CNTs present superior electrocatalytic activity and stability toward ORR and OER over the commercial Pt/C and IrO₂ as well as most reported metal‐organic‐framework‐derived catalysts, respectively. Remarkably, as bifunctional air electrodes of the Zn–air battery, it also shows extraordinary charge–discharge performance. The present concept will provide a guideline for screening novel 2D metal‐organic frameworks as precursors to synthesize advanced multifunctional nanomaterials for cross‐cutting applications.     

Highly Surface‐Wrinkled and N‐Doped CNTs Anchored on Metal Wire: A Novel Fiber‐Shaped Cathode toward High‐Performance Flexible Li–CO2 Batteries

Li–CO₂ batteries are regarded as a promising candidate for the next‐generation high‐performance electrochemical energy storage system owing to their ultrahigh theoretical energy density and environmentally friendly CO₂ fixation ability. Until now, the majority of reported catalysts for Li–CO₂ batteries are in the powder state. Thus, the air electrodes are produced in 2D rigid bulk structure and their electrochemical properties are negatively influenced by binder. The nondeformable feature and unsatisfactory performance of the cathode have already become the main obstacles that hinder Li–CO₂ batteries toward ubiquity for wearable electronics. In this work, for the first time, a flexible hybrid fiber is reported comprising highly surface‐wrinkled and N‐doped carbon nanotube (CNT) networks anchored on metal wire as the cathode integrated with high performance and high flexibility for fiber‐shaped Li–CO₂ battery. It exhibits a large discharge capacity as high as 9292.3 mAh g^?1, an improved cycling performance of 45 cycles, and a decent rate capability. A quasi‐solid‐state flexible fiber‐shaped Li–CO₂ battery is constructed to illustrate the advantages on mechanical flexibility of this fiber‐shaped cathode. Experiments and theoretical simulations prove that those doped pyridinic nitrogen atoms play a critical role in facilitating the kinetics of CO₂ reduction and evolution reaction, thereby enabling distinctly enhanced electrochemical performance.     

The Quasi‐Pt‐Allotrope Catalyst: Hollow PtCo@single‐Atom Pt1 on Nitrogen‐Doped Carbon toward Superior Oxygen Reduction

Single‐atom Pt and bimetallic Pt₃Co are considered the most promising oxygen reduction reaction (ORR) catalysts, with a much lower price than pure Pt. The combination of single‐atom Pt and bimetallic Pt₃Co in a highly active nanomaterial, however, is challenging and vulnerable to agglomeration under realistic reaction conditions, leading to a rapid fall in the ORR. Here, a sustainable quasi‐Pt‐allotrope catalyst, composed of hollow Pt₃Co (H‐PtCo) alloy cores and N‐doped carbon anchoring single atom Pt shells (Pt₁N‐C), is constructed. This unique nanoarchitecture enables the inner and exterior spaces to be easily accessible, exposing an extra‐high active surface area and active sites for the penetration of both aqueous and organic electrolytes. Moreover, the novel Pt₁N‐C shells not only effectively protect the H‐PtCo cores from agglomeration but also increase the efficiency of the ORR in virtue of the isolated Pt atoms. Thus, the H‐PtCo@Pt₁N‐C catalyst exhibits stable ORR without any fade over a prolonged 10 000 cycle test at 0.9 V in HClO₄ solution. Furthermore, this material can offer efficient and stable ORR activities in various organic electrolytes, indicating its great potential for next‐generation lithium–air batteries as well.     

Realizing the Intrinsic Electrochemical Activity of Acidic N‐Doped Graphene through 1‐Pyrenesulfonic Acid Bridges

Electrochemical technology attracts much research interest for the treatment of metal complexes, but most electrocatalysts are incapable of effectively degrading metal complexes, which generally have highly stable cages with five or six rings coordinating with metal ions. To address this, a bridging agent linking the catalysts and metal complexes can lower the energy barrier, and thus holds much promise to facilitate the removal of such pollutants. In this study, 1‐pyrenesulfonic acid (PSA) functionalization of acidic nitrogen‐doped graphene (ANG) is successfully synthesized and found to effectively remove metal complexes through electrochemical membrane filtration. Results indicate that PSA, interacting with Cu‐EDTA via the strong ion exchange of super acidic sulfonic (?SO₃H) groups, acts as a conductive “bridge” connecting the electrocatalyst and metal complexes to overcome the challenge with penetrating the “cage” structure of metal complexes. The pyrrolic nitrogen of ANG is found to be the active sites in the electrochemical process, with the intrinsic electrochemical activity realized by the bridging agent, namely, PSA. This study highlights the importance of compounds with sulfonyl groups in circumventing the stable “cage” of the metal complexes, and thereby paves the way for effective degradation of such pollutants.     

CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen‐Doped Carbon Nanotubes: A High‐Efficiency Bifunctional Oxygen Electrode for Zn–Air Batteries

The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo₂O₄ quantum dots (CuCo₂O₄/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo₂O₄ and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu²⁺ and Cu?N) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo₂O₄/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm^?2 in liquid state, 1.86 W g^?1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.     

Approaching the Downsizing Limit of Maricite NaFePO4 toward High‐Performance Cathode for Sodium‐Ion Batteries

Maricite NaFePO₄ nanodots with minimized sizes (≈1.6 nm) uniformly embedded in porous N‐doped carbon nanofibers (designated as NaFePO₄@C) are first prepared by electrospinning for maximized Na‐storage performance. The obtained flexible NaFePO₄@C fiber membrane adherent on aluminum foil is directly used as binder‐free cathode for sodium‐ion batteries, revealing that the ultrasmall nanosize effect as well as a high‐potential desodiation process can transform the generally perceived electrochemically inactive maricite NaFePO₄ into a highly active amorphous phase; meanwhile, remarkable electrochemical performance in terms of high reversible capacity (145 mA h g^?1 at 0.2 C), high rate capability (61 mA h g^?1 at 50 C), and unprecedentedly high cyclic stability (≈89% capacity retention over 6300 cycles) is achieved. Furthermore, the soft package Na‐ion full battery constructed by the NaFePO₄@C nanofibers cathode and the pure carbon nanofibers anode displays a promising energy density of 168.1 Wh kg^?1 and a notable capacity retention of 87% after 200 cycles. The distinctive 3D network structure of very fine NaFePO₄ nanoparticles homogeneously encapsulated in interconnected porous N‐doped carbon nanofibers, can effectively improve the active materials' utilization rate, facilitate the electrons/Na⁺ ions transport, and strengthen the electrode stability upon prolonged cycling, leading to the fascinating Na‐storage performance.     

Integrated Hierarchical Carbon Flake Arrays with Hollow P‐Doped CoSe2 Nanoclusters as an Advanced Bifunctional Catalyst for Zn–Air Batteries

Hierarchical nanostructured architectures are demonstrated as an effective approach to develop highly active and bifunctional electrocatalysts, which are urgently required for efficient rechargeable metal–air batteries. Herein, a mesoporous hierarchical flake arrays (FAs) structure grown on flexible carbon cloth, integrated with the microsized nitrogen‐doped carbon (N‐doped C) FAs, nanoscaled P‐doped CoSe₂ hollow clusters and atomic‐level P‐doping (P‐CoSe₂/N‐C FAs) is described. The P‐CoSe₂/N‐C FAs thus developed exhibit a reduced overpotential (≈230 mV at 10 mA cm^?2) toward oxygen evolution reaction (OER) and large half‐wave potential (0.87 V) for oxygen reduction reactions. The excellent bifunctional electrocatalytic performance is ascribed to the synergy among the hierarchical flake arrays controlled at both micro‐ and nanoscales, and atomic‐level P‐doping. Density functional theory calculations confirm that the free energy for the potential‐limiting step is reduced by P‐doping for OER. An all‐solid‐state zinc–air battery made of the P‐CoSe₂/N‐C FAs as the air‐cathode presents excellent cycling stability and mechanical flexibility, demonstrating the great potential of the hierarchical P‐CoSe₂/N‐C FAs for advanced bifunctional electrocatalysis.     

One‐Step Synthesis of W2C@N,P‐C Nanocatalysts for Efficient Hydrogen Electrooxidation across the Whole pH Range

Highly active and low‐cost non‐noble metal electrocatalysts for hydrogen oxidation reaction (HOR) are crucial for the large‐scale applications of fuel cells, which, unfortunately, are rarely documented up to now. Here, a facile one‐step strategy to fabricate W₂C nanoparticles (≈3 nm) encased in N, P‐doped few layer carbon materials (W₂C@N,P‐C, WNPC) as an efficient non‐noble metal HOR electrocatalyst simply by calcining the mixture of recrystallized phosphotungstic acid and dicyandiamide is reported. The obtained WNPC catalyst shows extraordinarily high HOR activities (1.03/0.91/0.84 mA cm^?2 at 0.05 V vs reversible hydrogen electrode in 0.1 m HClO₄/0.1 m KOH/0.1 m neutral phosphate buffered saline electrolytes, respectively), excellent durability during accelerated degradation tests for 10 000 cycles, and outstanding CO tolerance. These high performances are attributed to the uniform structure of WNPC, and more essentially, the synergistic effect among N, P, and C species which elevates the reducibility of WNPC, favoring the generation of abundant HOR active sites.     

Simple and Scalable Mechanochemical Synthesis of Noble Metal Catalysts with Single Atoms toward Highly Efficient Hydrogen Evolution

Designing a facile strategy to access active and atomically dispersed metallic catalysts are highly challenging for single atom catalysts (SACs). Herein, a simple and fast approach is demonstrated to construct Pt catalysts with single atoms in large quantity via ball milling Pt precursor and N‐doped carbon support (K₂PtCl₄@NC‐M; M denotes ball‐milling). The as‐prepared K₂PtCl₄@NC‐M only requires a low overpotential of 11 mV and exhibits 17‐fold enhanced mass activity for the electrochemical hydrogen evolution compared to commercial 20 wt% Pt/C. The superior hydrogen evolution reaction (HER) catalytic activity of K₂PtCl₄@NC‐M can be attributed to the generation of Pt single atoms, which improves the utilization efficiency of Pt atoms and the introduction of Pt‐N₂C₂ active sites with near‐zero hydrogen adsorption energy. This viable ball milling method is found to be universally applicable to the fabrication of other single metal atoms, for example, rhodium and ruthenium (such as Mt‐N₂C₂, where Mt denotes single metal atom). This strategy also provides a promising and practical avenue toward large‐scale energy storage and conversion application.     

Atomic‐Scale CoOx Species in Metal–Organic Frameworks for Oxygen Evolution Reaction

The activity of electrocatalysts strongly depends on the number of active sites, which can be increased by downsizing electrocatalysts. Single‐atom catalysts have attracted special attention due to atomic‐scale active sites. However, it is a huge challenge to obtain atomic‐scale CoO_x catalysts. The Co‐based metal–organic frameworks (MOFs) own atomically dispersed Co ions, which motivates to design a possible pathway to partially on‐site transform these Co ions to active atomic‐scale CoO_x species, while reserving the highly porous features of MOFs. In this work, for the first time, the targeted on‐site formation of atomic‐scale CoO_x species is realized in ZIF‐67 by O₂ plasma. The abundant pores in ZIF‐67 provide channels for O₂ plasma to activate the Co ions in MOFs to on‐site produce atomic‐scale CoO_x species, which act as the active sites to catalyze the oxygen evolution reaction with an even better activity than RuO₂.     

Fe3C‐Co Nanoparticles Encapsulated in a Hierarchical Structure of N‐Doped Carbon as a Multifunctional Electrocatalyst for ORR,OER, and HER

Rational design of non‐noble metal catalysts with robust and durable electrocatalytic activity for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is extremely important for renewable energy conversion and storage, regenerative fuel cells, rechargeable metal–air batteries, water splitting etc. In this work, a unique hybrid material consisting of Fe₃C and Co nanoparticles encapsulated in a nanoporous hierarchical structure of N‐doped carbon (Fe₃C‐Co/NC) is fabricated for the first time via a facile template‐removal method. Such an ingenious structure shows great features: the marriage of 1D carbon nanotubes and 2D carbon nanosheets, abundant active sites resulting from various active species of Fe₃C, Co, and NC, mesoporous carbon structure, and intimate integration among Fe₃C, Co, and NC. As a multifunctional electrocatalyst, the Fe₃C‐Co/NC hybrid exhibits excellent performance for ORR, OER, and HER, outperforming most of reported triple functional electrocatalysts. This study provides a new perspective to construct multifunctional catalysts with well‐designed structure and superior performance for clean energy conversion technologies.     

Embedding RhPx in N,P Co‐Doped Carbon Nanoshells Through Synergetic Phosphorization and Pyrolysis for Efficient Hydrogen Evolution

Rational design and controllable synthesis of well‐defined nanostructures with high stability and Pt‐like activity for hydrogen evolution reaction (HER) are critical for renewable energy conversion. Herein, a unique pyrolysis strategy is demonstrated for the synthesis of RhP_x nanoparticles (NPs) in N, P co‐doped thin carbon nanoshells (RhP_x@NPC nanoshells) that display high electrocatalytic activity and stability over a wide pH range. This strategy involves simultaneous phosphorization and pyrolysis processes that can produce highly‐dispersed RhP_x NPs within N, P co‐doped carbon nanoshells and at the same time induce thinning of carbon nanoshells from inside out. The resulting RhP_x@NPC nanoshells not only possess Pt‐like activity for HER with low overpotentials to achieve 10 mA cm^?2 (22 mV in 0.5 m H₂SO₄, 69 mV in 1.0 m KOH, and 38 mV in 1.0 m phosphate buffered saline (PBS)) but also provide long‐term durability in a wide pH range. The remarkable HER performance of RhP_x@NPC nanoshells is ascribed to the high surface area, abundant mesoporosity, strong catalyst–support interaction, ultrathin carbon encapsulation, and N, P co‐doping. This work provides an effective strategy for designing heterostructured electrocatalysts with high catalytic activity and stability desired for reactions that may occur under harsh conditions.     

Selenium‐Doped Hierarchically Porous Carbon Nanosheets as an Efficient Metal‐Free Electrocatalyst for CO2 Reduction

Electrochemical carbon dioxide reduction reaction (CO₂RR) provides a promising pathway for both decreasing atmospheric CO₂ concentration and producing valuable carbon‐based fuels. To explore efficient and cost‐effective catalysts for electrochemical CO₂RR is of great importance, but remains challenging. Se‐doped carbon nanosheets (Se‐CNs) with a micro‐, meso‐, and macroporous structure are proposed for electrochemical CO₂RR. Such an electrocatalyst combines the advantages of Se optimized active sites, hierarchical pores for facilitating reactant or ion penetration, transport and reaction, and large surface area for more accessible active sites. This Se‐CNs electrocatalyst exhibits over 11‐times enhanced partial current density of CO than the CNs without Se doping and high selectivity (90%) for CO₂ electroreduction to CO at a low potential of ?0.6 V versus the reversible hydrogen electrode (vs RHE). Density function theoretical calculations reveal that the Se introduction in CNs lowers the free energy barrier of CO₂RR and inhibits hydrogen evolution reaction effectively, thus improving the selectivity for CO₂ reduction to CO. This work presents a new member of the metal‐free electrocatalyst family, which is easily prepared, low cost, adjustable, and highly efficient for CO₂RR.     

Designing 3D Biomorphic Nitrogen‐Doped MoSe2/Graphene Composites toward High‐Performance Potassium‐Ion Capacitors

Potassium‐ion hybrid capacitors (KICs) reconciling the advantages of batteries and supercapacitors have stimulated growing attention for practical energy storage because of the high abundance and low cost of potassium sources. Nevertheless, daunting challenge remains for developing high‐performance potassium accommodation materials due to the large radius of potassium ions. Molybdenum diselenide (MoSe₂) has recently been recognized as a promising anode material for potassium‐ion batteries, achieving high capacity and favorable cycling stability. However, KICs based on MoSe₂ are scarcely demonstrated by far. Herein, a diatomite‐templated synthetic strategy is devised to fabricate nitrogen‐doped MoSe₂/graphene (N‐MoSe₂/G) composites with favorable pseudocapacitive potassium storage targeting a superior anode material for KICs. Benefiting from the unique biomorphic structure, high electron/K‐ion conductivity, enriched active sites, and the conspicuous pseudocapacitive effect of N‐MoSe₂/G, thus‐derived KIC full‐cell manifests high energy/power densities (maximum 119 Wh kg^?1/7212 W kg^?1), outperforming those of recently reported KIC counterparts. Furthermore, the potassium storage mechanism of N‐MoSe₂/G composite is systematically explored with the aid of first‐principles calculations in combination of in situ X‐ray diffraction and ex situ Raman spectroscopy/transmission electron microscopy/X‐ray photoelectron spectroscopy.