Three-dimensional Sn-doped CuO nanoflower grown on titanium foil (Sn-doped CuO/Ti) was synthesized via a facile hydrothermal method and evaluated as a binder-free anode for sodium-ion batteries. This unique anode host leverages Sn doping to significantly boost the electronic and ionic conductivity of CuO and induce rich Na+-ion storage sites, while its binder-free structure features can significantly improve electron transport and minimize interfacial polarization to accelerate fast Na+-ion transport kinetics and enhance cycling stability. Such synergistic effect underpins Sn-doped CuO/Ti anode exceptional performance, delivering a high reversible capacity of 489 mAh g-1 at 85 mA g-1, excellent rate capability (187 mAh g-1 at 250 mA g-1), and stable cycling performance with 87 % capacity retention after 400 cycles. The design strategy presented here opens a promising avenue for engineering novel anodes that combine high capacity with extended cycle life in sodium-ion batteries.

Sodium-ion batteries based on two-dimensional (2D) lamellar structural MoSe2 anode have emerged as a promising candidate thanks to its high theoretical capacity and favorable band gap structure. Yet, its intrinsic limitations involving poor conductivity, limited reaction reversibility, and unavoidable volumetric fluctuations upon cycling trigger severe structural degradation and capacity fading, ultimately resulting in inferior rate kinetics and unsatisfactory cycling durability. Herein, an innovative atomic-level interfacial coupling engineering is applied for fabricating a 2D hierarchical nanoarchitecture with ultrathin MoSe2 nanosheet grafting on graphene-like nitrogen-doped carbon-supported atomically dispersed NiN4Cl active sites (MoSe2@NiN4Cl-NC). Collaborative electrochemical analyses and computational modeling reveal that the NiN4Cl-NC architecture as an efficient nanoreactor can significantly optimize electronic conductivity and charge transfer efficiency while enhancing Na+-ion adsorption and migration capability, as well as reduce thermodynamic barriers for Na2Se/NaxMoSe2 decomposition, thereby achieving superior spatial confinement and reaction reversibility of active species. In-situ/ex-situ electrochemical analysis showcases high phase-transformation reversibility of MoSe2 during the sodiation and desodiation processes. Consequently, as-fabricated composites deliver an attractive rate capability and cyclic lifespan, that is, a capacity of 230 mAh g-1 at 20.0 A g-1 over 4600 cycles. Remarkably, the fabricated sodium-ion full cells and capacitors based on MoSe2@NiN4Cl-NC anode demonstrate excellent performance metrics and remarkable energy/power density, collectively validating its potential proof-of-feasibility in practical use.

Electrocatalytic C-N coupling of nitrate and CO2 represents a paradigm shift in sustainable urea synthesis. We demonstrate that amorphous CuOx-coated crystalline Cu nanowires achieve a record-breaking urea yield rate of 0.89 mol h-1 g-1 via novel electrochemical-chemical looping. Mechanistic investigations reveal a three-step catalytic cycle: (i) electro-reductive generation of Cu0 and oxygen vacancies (Ov); (ii) Ov-mediated nitrate activation via oxygen atom insertion, spontaneously yielding nitrogen-bonded nitrite (*NO2) while oxidizing Cu0 to catalytically active Cu+; and (iii) Cu+-catalyzing C-N coupling between *NO2 and CO2 to form urea. This pathway circumvents conventional rate-limiting nitrate reduction step, reducing the electron transfer requirement from 16e- to 12e- for urea synthesis. Notably, direct nitrite utilization fails to generate Cu+ or nitrogen-bonded intermediates, instead forming oxygen-bonded species with markedly reduced C-N coupling activity-a finding that overturns conventional understanding. Our work establishes new fundamental principles for efficient urea synthesis and provides insights into catalyst design and green chemistry.

Through inducing interlayer anionic ligands and functionally modifying conductive carbon-skeleton on the transition metal chalcogenides (TMCs) parent to achieve atomic-level defect-manipulation and nanoscopic-level architecture design is of great significance, which can broaden interlayer distance, optimize electronic structure, and mitigate structural deformation to endow high-efficiency battery performance of TMCs. Herein, an intriguing 3D biconcave hollow-tyre-like anode constituted by carbon-packaged defective-rich SnSSe nanosheet grafting onto Aspergillus niger spores-derived hollow-carbon (ANDC@SnSSe@C) is reported. Systematically experimental investigations and theoretical analyses forcefully demonstrate the existence of anion Se ligand and outer-carbon all-around encapsulation on the ANDC@SnSSe@C can effectively yield abundant structural defects and Na+-reactivity sites, accelerate rapid ion migration, widen interlayer spacing, as well as relieve volume expansion, thus further resolving the critical issues throughout the charge-discharge processes. As anticipated, as-fabricated ANDC@SnSSe@C anode contributes extraordinary reversible capacity, wonderful cyclic lifespan with 83.4% capacity retention over 2000 cycles at 20.0 A g-1, and exceptional rate capability. A series of correlated kinetic investigations and ex situ characterizations deeply reveal the underlying springheads for the ion-transport kinetics, as well as synthetically elucidate phase-transformation mechanism of the ANDC@SnSSe@C. Furthermore, the ANDC@SnSSe@C-based sodium ion full cell and hybrid capacitor offer high-capacity contribution and remarkable energy-density output, indicative of its great practicability. Carbon-packaged defective-rich SnSSe nanosheets grafted onto Aspergillus niger spores-derived hollow-carbon (ANDC@SnSSe@C) is constructed. Benefiting from the remarkable advantages of ingenious nanoarchitectures, the ANDC@SnSSe@C composites afford a remarkable long-cycle durability and admirable high-rate capability. image

Electrocatalytic reduction of nitrate (NO3-) is a promising approach to achieving sustainable and green ammonia synthesis and environmental denitrification. Here, click chemistry is extended to fabricate dynamic single-site metal catalysts for NO3- electroreduction. Specifically, Co2+-coordinated molecular units are covalently clicked into a stable Th-metal-organic framework, confining and dispersing single-site metals that exhibit the asymmetrical Co-N2Cl2 coordination configuration. The obtained CoN2Cl2@Th-BPDC electrocatalyst achieves an outstanding ammonia production rate of 770.3 mu mol h(-1) cm(-2) (5135.3 mmol g(cat)(-1) h(-1)) at -0.4 V versus RHE, which is approximately 25.7 times higher than that of the Haber-Bosch process (<200 mmol g(cat)(-1) h(-1)) and outperforms the most recently reported electrocatalysts. Theoretical calculations reveal that single-site Co2+ exhibits strong bidentate adsorption toward NO3- due to the suitable geometric space provided by the rotation of Co-coordinated Cl atoms (a dynamic feature), which promotes NO3- activation and decreases the reaction barrier, resulting in excellent catalytic activity. This study describes an innovative strategy for fabricating dynamic asymmetrical single-site metal electrocatalysts and may inspire new methodologies for the precise synthesis of advanced catalytic materials.

New‐fashioned electrode hosts for sodium‐ion batteries (SIBs) are elaborately engineered to involve multifunctional active components that can synergistically conquer the critical issues of severe volume deformation and sluggish reaction kinetics of electrodes toward immensely enhanced battery performance. Herein, it is first reported that single‐phase CoPS, a new metal phosphosulfide for SIBs, in the form of quantum dots, is successfully introduced into a leaf‐shaped conductive carbon nanosheet, which can be further in situ anchored on a 3D interconnected branch‐like N‐doped carbon nanofiber (N‐CNF) to construct a hierarchical branch‐leaf‐shaped CoPS@C@N‐CNF architecture. Both double carbon decorations and ultrafine crystal of the CoPS in‐this exquisite architecture hold many significant superiorities, such as favorable train‐relaxation, fast interfacial ion‐migration, multi‐directional migration pathways, and sufficiently exposed Na + ‐storage sites. In consequence, the CoPS@C@N‐CNF affords remarkable long‐cycle durability over 10 000 cycles at 20.0 A g −1 and superior rate capability. Meanwhile, the CoPS@C@N‐CNF‐based sodium‐ion full cell renders the potential proof‐of‐feasibility for practical applications in consideration of its high durability over a long‐term cyclic lifespan with remarkable reversible capacity. Moreover, the phase transformation mechanism of the CoPS@C@N‐CNF and fundamental springhead of the enhanced performance are disclosed by in situ X‐ray diffraction, ex situ high‐resolution TEM, and theoretical calculations.

Twin boundary (TB) engineering provides exciting opportunities to tune the performance levels of metal-based electrocatalysts. However, the controllable construction of TB greatly relies on surfactants, blocking active sites, and electron transfer by surfactants. Here, a surfactant-free and facile strategy is proposed for synthesizing copper (Cu) nanocatalysts with dense hierarchical TB networks (HTBs) by the rapid thermal reductions in metastable CuO nanosheets in H2 . As revealed by in situ transmission electron microscopy, the formation of HTBs is associated with the fragmentation of nanosheets in different directions to generate abundant crystal nuclei and subsequently unconventional crystal growth through the collision and coalescence of nuclei. Impressively, the HTBs endow Cu with excellent electrocatalytic performance for direct nitrate-ammonia conversion, superior to that of Cu with a single-oriented TB and without TB. It is discovered that the HTBs induce the formation of compressive strains, thereby creating a synergistic effect of TBs and strains to efficiently tune the binding energies of Cu with nitrogen intermediates (i.e., NO2 *) and thus promote the tandem reaction process of NO3 - -to-NO2 - and subsequent NO2 - -to-NH3 electrocatalysis. This work demonstrates the crucial role of HTBs for boosting electrocatalysis via the synergistic effect of TBs and strains.

Juncus-derived three-dimensional interconnected tubular carbon network decorated with tiny solid-solution metal sulfide nanoparticles favorably affords affluent active sites and porous channels, thus endowing superior sodium-storage performance.

A wide diversity of phosphides of platinum-group metal including Rh, Ru and Ir exhibit intriguing electrocatalytic activity toward hydrogen evolution reaction (HER). The phosphidation degree, namely the P dosage in these phosphides shows pronounced influence on the catalytic performance but is hard to control. In this work we developed a reliable strategy to synthesize Rh2P-based nanoparticles with controlled phosphidation degree, and investigated the influence of phosphidation degree on HER. It is found that the heterostructured Rh2P/Rh nanoparticle, i.e., the P-deficient composite with mixed metallic and phosphide phases, outperforms either the metallic Rh or pure Rh2P nanoparticles. As-synthesized Rh2P/Rh nanoparticles supported on P/N co-doped graphene (denoted as Rh2P/Rh-G) display remarkable HER activity with tiny overpotential of 17 and 19 mV at 10 mA cm(-2) current density in alkaline and acid, efficiently surpassing its Rh-based rivals and benchmark Pt/C catalyst. Meanwhile it illustrates a large mass-specific activity (3.23 and 6.26 A mg(-1)@50 mV overpotential in alkaline and acid, respectively) due to its high activity and low metal loading. Density functional theory (DFT) calculation indicates that the Rh2P/Rh heterostructured interface possesses the optimal close-to-zero value of hydrogen adsorption energy and water dissociation process is accelerated, and thus boosts HER activity. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Exploration of earth-abundant, low cost, and versatile catalysts with Pt-like performance for electrochemical water splitting holds practical significance for clean energy shortage and environmental pollution. However, manipulating the electronic structure and relevant physical properties of the catalysts is crucial in promoting their hydrogen evolution reaction (HER) performance but still a formidable challenge. In this work, we report a self-supported dual-metal doped on CoP3 nanowire arrays (NAs) and grown on carbon fiber cloth (Ni,Mn-CoP3 NAs) for alkaline HER. The optimized catalyst exhibits superior electrocatalytic activity, giving a low overpotential of 24 mV at 10 mA cm−2 with a small Tafel slope of 41 mV dec−1 and can sustain for 24 h, which is superior to the commercial Pt/C catalysts at a large current density. On the basis of systematic experiments and density functional theory calculations, the synergistic regulation of dual-metal doping can re-form the electronic structure so as to enhance the electrical conductivity, improve the intrinsic HER activity, and increase the electrochemical surface area of CoP3. This work points out avenues in the reasonable design and development of dual-metal doped transition-metal phosphides as highly active, durable, and economically viable catalysts for various catalytic reactions.

Ru-based nanomaterials are among the best electrocatalysts for hydrogen evolution reaction (HER) in alkaline media, however their stability is still questionable, especially under harsh conditions towards practical applications (i.e., 80 degrees C, 6 M KOH). We demonstrate that the conventionally surface-supported Ru electrocatalysts are actually not stable under harsh conditions due to the weak interaction between Ru and supports, although they are stable under mild conditions. Here, we report a lattice-confined approach to concurrently enhance the stability and intrinsic activity of Ru via confining ultrafine Ru clusters into TiO2 lattice frameworks. Impressively, such confined Ru delivers outstanding performance for HER under harsh conditions, such as a small overpotenital of 116 mV at 800 mA cm(-2), and long-time stability for 200-h continuous HER at 300 mA cm(-2). As uncovered by both computational and experimental results, the lattice-confined strategy can significantly enhance the interaction between Ru and TiO2 for promoting the electron transfer from Ru to TiO2, thereby strongly stabilizing Ru for avoiding the dissociation and aggregation of Ru during the stability test. Therefore, the lattice-confined strategy may stand out as a robust approach for boosting the activity and stability of electrocatalysts.

Rh was incorporated in Fe-doped Ni3S2 nanosheets with the assistance of hydrogen plasma to significantly enhance the HER/OER catalytic activity. The operando evolution behavior and Janus catalytic mechanism of this catalyst were further revealed.

Subnanometric metal clusters usually have unique electronic structures and may display electrocatalytic performance distinctive from single atoms (SAs) and larger nanoparticles (NPs). However, the electrocatalytic performance of clusters, especially the size-activity relationship at the sub-nanoscale, is largely unexplored. Here, we synthesize a series of Ru nanocrystals from single atoms, subnanometric clusters to larger nanoparticles, aiming at investigating the size-dependent activity of hydrogen evolution in alkaline media. It is found that the d band center of Ru downshifts in a nearly linear relationship with the increase of diameter, and the subnanometric Ru clusters with d band center closer to Femi level display a stronger water dissociation ability and thus superior hydrogen evolution activity than SAs and larger nanoparticles. Benefiting from the high metal utilization and strong water dissociation ability, the Ru clusters manifest an ultrahigh turnover frequency of 43.3 s −1 at the overpotential of 100 mV, 36.1-fold larger than the commercial Pt/C.

Electrochemical nitrate reduction reaction (NO3-RR) is an ideal route to produce ammonia (NH3) under ambient conditions. Although a markedly improved NH3 production rate has been achieved on the NO3-RR compared with the nitrogen reduction reaction (NRR), the NH3 production rate of NO3-RR is still well below the industrial Haber-Bosch route due to the lack of robust electrocatalysts for yielding high current densitieswith concurrently good suppression of hydrogen evolution reaction (HER). Herein, we describe an in situ electrochemical strategy for the synthesis of hollow carbon-coated Cu nanoparticles (NPs) (HSCu@C) with abundant grain boundaries (HSCu-AGB@C) for highly efficient NO3-RR in both alkaline and neutral media. Impressively, in alkaline media, the HSCu-AGB@C can achieve a maximum NH3 Faradaic efficiency of 94.2% with an ultrahigh NH3 rate of 487.8 mmol g(-1) cat h(-1) at -0.2 V versus a reversible hydrogen electrode, more than 2.4-fold of the rate obtained in the Haber-Bosch. Both theoretic computations and experimental results uncover that the grain boundaries play the key to improve the NO3-RR performance. Herein, the industrial-scale NH3 production ratemay open exciting opportunities for the practical electrosynthesis NH3 under ambient conditions. [GRAPHICS]

Renewable-electricity-powered electrochemical CO 2 reduction reactions (CO 2 RR) to highly value-added multi-carbon (C 2+ ) fuels or chemicals have been widely recognized as a promising approach for achieving carbon recycling and thus bringing about sustainable environmental and economic benefits. Cu-based catalysts have been demonstrated as the only candidate metal CO 2 RR electrocatalysts that catalyze the C–C coupling. Unfortunately, huge challenges still exist in the highly selective CO 2 RR to C 2+ products due to the higher activation barrier of C–C coupling and complex multi-electron reaction. Key fundamental issues regarding both active species and product formation pathways have not been elucidated by now, but recent developments of advanced strategies and characterization tools allow one to comprehensively understand the Cu-based CO 2 RR mechanism. Herein, we review recent advance and perspective of Cu-based CO 2 RR catalysts, especially in terms of active phases and product formation pathways. Then, strategies in catalysts design for CO 2 RR toward C 2+ products are also presented. Importantly, we systematically summarized the advanced tools for investigating the CO 2 RR mechanism, including in situ/operando spectroscopy techniques, isotope labeling, and theoretical calculations, aiming at unifying the knowledge of active species and product formation pathways. Finally, future challenges and constructive perspectives are discussed, facilitating the accelerated advancement of CO 2 RR mechanism research. Graphical Abstract

Electrocatalytic urea oxidation reaction (UOR) presents lower thermodynamic potential than oxygen evolution reaction (OER), thus exhibiting promising potential to enhance the efficiency of overall water splitting. However, due to the intrinsically sluggish six-electron transfer process, the efficiency of UOR is still not satisfied. In response, we synthesized a bimetallic NiFe-MIL-53-NH2 with superior activity toward UOR, which only needs a low potential of 1.398 V vs. RHE to obtain 50 mA cm(-2) in 1.0 M KOH with 0.33 M urea, much lower than that in 1.0 M KOH (1.721 V vs. RHE). Furthermore, NiFe-MIL-53-NH2 presents significantly more excellent UOR activity compared to its monometallic counterparts. The TOF value in NiFe-MIL-53-NH2 (0.16 s(-1)) at 1.4 V vs. RHE is about 133- and 246-folds higher than that Ni-MIL-53-NH2 (1.2 x 10(-3) s(-1)) and Fe-MIL-53-NH2 (6.5 x 10(-)(4) s(-1)), respectively. XPS characterization discloses that the incorporation of Fe into Ni-MIL-53-NH2 framework optimizes the local charge distribution of metal nodes, leading to the formation of electrophilic Ni3+ and nucleophilic Fe3+ species, which can absorb electron-donating -NH2 and electron-withdrawing C = O groups in urea, respectively, and therefore result in excellent UOR. This simple strategy of regulating local charge distribution of active species by fabricating bimetallic MOFs provides a new strategy and direction to explore other highly efficient UOR electrocatalysts.

Electrochemical nitrate (NO3-) reduction reaction (NO3-RR) offers an ideal route to harvest ammonia (NH3) under ambient conditions. Despite recent advances in Cu-based NO3-RR electrocatalysts, their synthesis heavily relies on the regulation of adsorption strength towards nitrogen-containing intermediates, and other important factors are ignored (i.e., the proton transfer rate). Here, we select Cu nanoparticles (NPs) as model catalysts to investigate whether and how the proton transfer rate impacts the NO3-RR kinetics. The results indicate that the proton transfer is involved in the rate-determining step (RDS) of NO3-RR, and the weak water dissociation ability of Cu leads to slow proton transfer rate and consequently sluggish NO3-RR kinetics. To this end, we enhance the water dissociation ability of Cu NPs by incorporating uncoordinated carboxylate ligands to enable rapid proton transfer, which in turn boosts the hydrogenation of key intermediates for reducing the overall energy barrier of NO3-RR. As a result, Cu NPs with the ligands display a maximum NH3 yield rate of 496.4 mmol h(-1) gcat performing counterpart without ligands. This work not only deepens our knowledge on the NO3-RR mechanism, but also offers new guidelines for the smart design of efficient electrocatalysts.

Yolk–shell NiS2/CuS hollow microspheres as an extraordinary kinetically pseudocapacitive nanoreactor for sodium-ion batteries manifest superb Na+-storage capability, including an ultrahigh ICE of 94.0%, remarkable specific capacity of 410.9 mA h g−1 after 750 cycles at 2.0 A g−1, excellent rate capability, and prolonged cyclability in terms of a remarkable retention of 283.4 mA h g−1 even after 4200 cycles at 20.0 A g−1.

Electrochemical nitrate (NO 3 − ) reduction reaction (NO 3 − RR) represents an ideal alternative for ammonia (NH 3 ) generation. Despite recent success on the synthesis of Cu-based electrocatalysts, the kinetics of Cu-catalyzed NO 3 − RR is still greatly limited by the slow proton transfer rate since the large energy barrier for water dissociation. Here, we report the construction of a yolk-shell structure, comprising a Cu core and Cu 2 Se shell that functions like the tandem nanoreactor. Specific, the Cu 2 Se shell with strong water dissociation ability can easily produce protons and then transfer to the Cu core for driving the reduction of NO 3 − . Intriguingly, the proton flux arriving to the Cu core can be well tuned by altering the void size of the yolk-structure, thereby enabling rapid proton transfer yet hindering the competitive hydrogen evolution. More importantly, operando Raman spectra reveal that the rapid proton transfer significantly promotes the hydrogenation of key intermediates for reducing the overall energy barrier of the NO 3 − RR. Consequently, the optimized yolk-shell structure enables highly selective and efficient NO 3 − RR with a large NH 3 yield rate of 0.94 mmol cm −2 h −1 . This work offers a fresh concept to boost the NO 3 − RR by tuning proton transfer rate.

A hierarchical core–shell architecture of vertically arrayed ultrathin CuSe nanosheets decorating on hollow CuS microcages affords exceptional sodium storage performance with an admirable 303.1 mA h g−1 at 20.0 A g−1 after 1500 cycles.