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Hybrid materials, integrating the merits of individual components, are ideal structures for efficient oxygen evolution reaction (OER). However, the rational construction of hybrid structures with decent physical/electrochemical properties is yet challenging. Herein, a promising OER electrocatalyst composed of trimetallic metal-organic frameworks supported over S/N-doped carbon macroporous fibers (S/N-CMF@FexCoyNi1-x-y-MOF) via a cation-exchange strategy is delicately fabricated. Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N-CMF matrix facilitating exposure of active sites, as well as their robust integration, the resultant S/N-CMF@FexCoyNi1-x-y-MOF electrocatalyst delivers outstanding activity and stability for alkaline OER. Specifically, it needs an overpotential of 296 mV to reach the benchmark current density of 10 mA cm−2 with a small Tafel slope of 53.5 mV dec−1. In combination with X-ray absorption fine structure spectroscopy and density functional theory calculations, the post-formed Fe/Co-doped γ-NiOOH during the OER operation is revealed to account for the high OER performance of S/N-CMF@FexCoyNi1-x-y-MOF. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2019-T2-2-049).

Mn-based oxides have sparked extensive scientific interest for aqueous Zn-ion batteries due to the rich abundance, plentiful oxidation states, and high output voltage. However, the further development of Mn-based oxides is severely hindered by the rapid capacity decay during cycling. Herein, a two-step metal-organic framework (MOF)-engaged templating strategy has been developed to rationally synthesize heterostructured Mn 2 O 3 -ZnMn 2 O 4 hollow octahedrons (MO-ZMO HOs) for stable zinc ion storage. The distinctive composition and hollow heterostructure endow MO-ZMO HOs with abundant active sites, enhanced electric conductivity, and superior structural stability. By virtue of these advantages, the MO-ZMO HOs electrode shows high reversible capacity, impressive rate performance, and outstanding electrochemical stability. Furthermore, ex situ characterizations reveal that the charge storage of MO-ZMO HOs mainly originates from the highly reversible Zn 2+ insertion/extraction reactions.

The development of efficient oxygen electrocatalysts and understanding their underlying catalytic mechanism are of significant importance for the high-performance energy conversion and storage technologies. Herein, we report novel CoCu-based bimetallic metal-organic framework nanoboxes (CoCu-MOF NBs) as promising catalysts toward efficient electrochemical oxygen evolution reaction (OER), fabricated via a successive cation and ligand exchange strategy. With the highly exposed bimetal centers and the well-designed architecture, the CoCu-MOF NBs show excellent OER activity and stability, with a small overpotential of 271 mV at 10 mA cm-2 and a high turnover frequency value of 0.326 s-1 at an overpotential of 300 mV. In combination of quasi in situ X-ray absorption fine structure spectroscopy and density-functional theory calculations, the post-formed CoCu-based oxyhydroxide analogue during OER is believed to account for the high OER activity of CoCu-MOF NBs, where the electronic synergy between Co and neighbouring Cu atoms promotes the O-O bond coupling toward fast OER kinetics.

Exploring earth-abundant electrocatalysts with excellent activity, robust stability, and multiple functions is crucial for electrolytic hydrogen generation. Porous phosphorized CoNi2 S4 yolk-shell spheres (P-CoNi2 S4 YSSs) were rationally designed and synthesized by a combined hydrothermal sulfidation and gas-phase phosphorization strategy. Benefiting from the strengthened Ni3+ /Ni2+ couple, enhanced electronic conductivity, and hollow structure, the P-CoNi2 S4 YSSs exhibit excellent activity and durability towards hydrogen/oxygen evolution and urea oxidation reactions in alkaline solution, affording low potentials of -0.135 V, 1.512 V, and 1.306 V (versus reversible hydrogen electrode) at 10 mA cm-2 , respectively. Remarkably, when used as the anode and cathode simultaneously, the P-CoNi2 S4 catalyst merely requires a cell voltage of 1.544 V in water splitting and 1.402 V in urea electrolysis to attain 10 mA cm-2 with excellent durability for 100 h, outperforming most of the reported nickel-based sulfides and even noble-metal-based electrocatalysts. This work promotes the application of sulfides in electrochemical hydrogen production and provides a feasible approach for urea-rich wastewater treatment.

The exploration of earth-abundant and efficient electrocatalysts toward the oxygen evolution reaction (OER) is critical for sustainable energy storage and conversion devices. In this work, we report a self-engaged strategy to fabricate a yolk-shelled OER electrocatalyst. Starting with a metal-organic framework, Co-Fe layered double hydroxide (LDH)@zeolitic imidazolate framework-67 (ZIF-67) yolk-shelled structures are formed in one step. Afterwards, these ZIF-67 building blocks are transformed into Ni-Co LDH nanocages to form the Ni-Co-Fe hydr(oxy)oxide@Ni-Co LDH yolk-shelled microrods (NiCoFe-HO@NiCo-LDH YSMRs) through an ion-exchange reaction. Owing to the structural and compositional merits, the NiCoFe-HO@NiCo-LDH YSMR electrocatalyst exhibits an overpotential of 278 mV to reach the current density of 10 mA cm

Prussian blue analogs (PBAs) are considered as reliable and promising cathode materials for aqueous Zn‐ion batteries (AZIBs), but they suffer from low capacity and poor cycling stability due to insufficient active sites and structural damage caused by the ion insertion/extraction processes. Herein, a template‐engaged ion exchange approach has been developed for the synthesis of Co‐substituted Mn‐rich PBA hollow spheres (CoMn‐PBA HSs) as cathode materials for AZIBs. Benefiting from the multiple advantageous features including hollow structure, abundant active sites, fast Zn2+ ion diffusion, and partial Co substitution, the CoMn‐PBA HSs electrode shows efficient zinc ion storage properties in terms of high capacity, decent rate capability and prolonged cycle life., Co‐substituted Mn‐rich Prussian Blue Analog (PBA) hollow spheres (CoMn‐PBA HSs) are rationally designed and synthesized through an efficient self‐templating approach. Benefiting from the hollow structure and partial Co substitution, the CoMn‐PBA HSs electrode exhibits enhanced zinc ion storage performance with high capacity, favorable rate capability, and impressive cycling stability.

The unique structural characteristics of one-dimensional (1D) hollow nanostructures result in intriguing physicochemical properties and wide applications, especially for electrochemical energy storage applications. In this Minireview, we give an overview of recent developments in the rational design and engineering of various kinds of 1D hollow nanostructures with well-designed architectures, structural/compositional complexity, controllable morphologies, and enhanced electrochemical properties for different kinds of electrochemical energy storage applications (i.e. lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, lithium-selenium sulfur batteries, lithium metal anodes, metal-air batteries, supercapacitors). We conclude with prospects on some critical challenges and possible future research directions in this field. It is anticipated that further innovative studies on the structural and compositional design of functional 1D nanostructured electrodes for energy storage applications will be stimulated. Ministry of Education (MOE) X.W.L. acknowledges funding support from the Ministry of Education of Singapore via the AcRF Tier-1 grant (RG3/20)

The development of efficient and low-cost electrocatalysts toward the oxygen evolution reaction (OER) is critical for improving the efficiency of several electrochemical energy conversion and storage devices. Here, we report an elaborate design and synthesis of porous Co-based trimetallic spinel oxide nanoboxes (NiCo2-x Fex O4 NBs) by a novel metal-organic framework engaged strategy, which involves chemical etching, cation exchange, and subsequent thermal oxidation processes. Owing to the structural and compositional advantages, the optimized trimetallic NiCo2-x Fex O4 NBs (x is about 0.117) deliver superior electrocatalytic performance for OER with an overpotential of 274 mV at 10 mA cm-2 , a small Tafel slope of 42 mV dec-1 , and good stability in alkaline electrolyte, which is much better than that of Co-based bi/monometallic spinel oxides and even commercial RuO2 .

Physicochemical confinement and catalytic conversion of lithium polysulfides (LiPSs) are crucial to suppress the shuttle effect and enhance the redox kinetics of lithium-sulfur (Li-S) batteries. In this study, a NH4Cl-assisted pyrolysis strategy is developed to fabricate highly mesoporous N-rich carbon (designed as NC(p)) featuring thin outer shells and porous inner networks, on which single-Ni atoms are anchored to form an excellent sulfur host (designed as Ni-NC(p)) for Li-S batteries. During pyrolysis, the pyrolytic HCl from confined NH4Cl within ZIF-8 will in situ etch ZIF-8 to produce rich mesoporous in the carbonized product NC(p). The mesoporous Ni-NC(p) enables favorable electron/ion transfer, high sulfur loading, and effective confinement of LiPSs, while the catalytic effect of single-Ni species enhances the redox kinetics of LiPSs. As a result, the sulfur cathode based on the Ni-NC(p) host delivers obviously improved Li-S battery performance with high specific capacity, good rate capability, and cycling stability. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2019-T2-2-049).

Prussian blue analogs (PBAs) are promising candidates for aqueous Zn-ion batteries due to their unique open-framework structures. However, they suffer from limited capacity and severe capacity decay originating from insufficient redox sites and structural instability. Herein, Cu-substituted Mn-PBA double-shelled nanoboxes (CuMn-PBA DSNBs) prepared by tannic acid etching and cation exchange approaches are demonstrated for efficient Zn ion storage. The unique hollow structures can expose abundant active sites and alleviate the volume change during the cycling test. Moreover, partial Cu substitution and induced Mn vacancies might inhibit the Jahn-Teller distortions of Mn-N6 octahedra, thus contributing to the prolonged lifespan. As a result, CuMn-PBA DSNBs exhibit high reversible capacity, decent rate performance and superior cycling stability for 2000 cycles. Furthermore, ex situ characterizations reveal that the charge storage mechanism of CuMn-PBA DSNBs mainly involves the reversible redox reactions of transition metals and Zn2+ ion insertion/extraction processes. Ministry of Education (MOE) X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-1 grant (RG3/20).

Despite suffering from slow charge-carrier mobility, photocatalysis is still an attractive and promising technology toward producing green fuels from solar energy. An effective approach is to design and fabricate advanced architectural materials as photocatalysts to enhance the performance of semiconductor-based photocatalytic systems. Herein, metal-organic-framework-derived hierarchically ordered porous nitrogen and carbon co-doped ZnO (N-C-ZnO) structures are developed as nanoreactors with decorated CoO

Developing electrocatalytic energy conversion technologies for replacing the traditional energy source is highly expected to resolve the fossil fuel exhaustion and related environmental problems. Exploring stable and high-efficiency electrocatalysts is of vital importance for the promotion of these technologies. Single-atom catalysts (SACs), with atomically distributed active sites on supports, perform as emerging materials in catalysis and present promising prospects for a wide range of applications. The rationally designed near-range coordination environment, long-range electronic interaction and microenvironment of the coordination sphere cast huge influence on the reaction mechanism and related catalytic performance of SACs. In the current Review, some recent developments of atomically dispersed reactive centers for electrocatalytic CO2 reduction and water splitting are well summarized. The catalytic mechanism and the underlying structure-activity relationship are elaborated based on the recent progresses of various operando investigations. Finally, by highlighting the challenges and prospects for the development of single-atom catalysis, we hope to shed some light on the future research of SACs for the electrocatalytic energy conversion. Ministry of Education (MOE) National Research Foundation (NRF) Published version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2017-T2-2-003) and Tier1 grant (RG116/18), and the National Research Foundation (NRF) of Singapore via the NRF Investigatorship (NRFNRFI2016-04).

Isolated cobalt atoms have been successfully decorated onto the surface of W18O49 ultrathin nanowires. The Co-atom-decorated W18O49 nanowires (W18O49@Co) greatly accelerate the charge carrier separ...

The advances in process engineering, nanotechnology, and materials science gradually enable the potential applications of biomass in novel energy storage technologies such as lithium secondary batteries (LSBs). Of note, biomass-derived materials that range from inorganic multi-dimensional carbons to renewable organic biomolecules or biopolymers can contribute towards “green battery” systems, serving as sustainable battery components. This review offers a comprehensive overview of the fabrication and application of both biomass and biomass-derived materials in LSBs. First, the processing routes of biomass towards different products are considered and described. The corresponding mechanistic understanding of biomass processing is particularly underscored. Classified by the battery components, focused discussions on biomass applied as electrode scaffolds, active cathode/anode materials, binders/additives, and separators/solid-state electrolyte layers in LSBs are systematically provided. The insights from this review demonstrate that biomass has significant potential for the development of high-performance “green battery” systems, which to different extents employ sustainable and green biomass-derived battery components. To accelerate its industrialization, specific attention should be paid to upgrading the processing technologies to maximize biomass utilization with high efficiency and low cost. Meanwhile, we summarize the present limitations over the application of biomass in LSBs and propose potential strategies for revolution. Additionally, we foresee further use of biomaterials to advance LSBs and other alkali-metal secondary batteries. This review comprehensively describes the significance of biomass and biomass-derived materials that have already received some attention and will bring numerous breakthroughs in the battery community. It is intended to attract the broad attention of scientists to this prospective trend of development in “green batteries”. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version

Confining nanostructured electrode materials in porous carbon represents an effective strategy for improving the electrochemical performance of lithium-ion batteries. Herein, we report the design and synthesis of hybrid hollow nanostructures composed of highly dispersed Co3 O4 hollow nanoparticles (sub-20 nm) embedded in the mesoporous walls of carbon nanoboxes (denoted as H-Co3 O4 @MCNBs) as an anode material for lithium-ion batteries. The facile metal-organic framework (MOF)-engaged strategy for the synthesis of H-Co3 O4 @MCNBs involves chemical etching-coordination and subsequent two-step annealing treatments. Owing to the unique structural merits including more active interfacial sites, effectively alleviated volume variation, good and stable electrical contact, and easy access of Li+ ions, the H-Co3 O4 @MCNBs exhibit excellent lithium-storage performance in terms of high specific capacity, excellent rate capability, and cycling stability. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2017-T2-2-003), and the National Research Foundation (NRF) of Singapore via the NRF Investigatorship (NRF-NRFI2016-04).

Developing noble-metal-free bifunctional oxygen electrocatalysts is of great significance for energy conversion and storage systems. Herein, we have developed a transformation method for growing NiMn-based bimetal-organic framework (NiMn-MOF) nanosheets on multi-channel carbon fibers (MCCF) as a bifunctional oxygen electrocatalyst. Owing to the desired components and architecture, the MCCF/NiMn-MOFs manifest comparable electrocatalytic performance towards oxygen reduction reaction (ORR) with the commercial Pt/C electrocatalyst and superior performance towards oxygen evolution reaction (OER) to the benchmark RuO2 electrocatalyst. X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations reveal that the strong synergetic effect of adjacent Ni and Mn nodes within MCCF/NiMn-MOFs effectively promotes the thermodynamic formation of key *O and *OOH intermediates over active NiO6 centers towards fast ORR and OER kinetics. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-1 funding (RG116/18), and the National Research Foundation (NRF) of Singapore via the NRF Investigatorship (NRF-NRFI2016-04). The authors thank Dr. Shibo Xi and the X-ray absorption fine structure for catalysis (XAFCA) beamline of the Singapore Synchrotron Light Source (SSLS) for supporting the XAFS measurements.

Single-atom catalysts (SACs), in which the metal active sites are isolated on the support and stabilized by coordinated atoms such as oxygen, nitrogen, sulfur, etc., represent the maximum usage efficiency of the metal atoms. Benefiting from the recent progress in synthetic strategies, characterization methods, and computational models, many SACs that deliver an impressive catalytic performance for a variety of reactions have been developed. The catalytic selectivity and activity are critical issues that need to be optimized and augmented in the areas of nanotechnology and biomedicine. This review summarizes some recent experimental and theoretical progress aimed at clarifying the structure of SACs and how they influence the catalytic performance. The examples described here elaborate on the utility of SACs and highlight the strengths of these catalysts in the applications of biomedicine, environmental protection, and energy conversion. Finally, some current challenges and future perspectives for SACs are also discussed., Some recent experimental and theoretical progress is summarized, aimed at clarifying the structure of single-atom catalysts and how they influence the catalytic performance.

The growth of Li dendrites hinders the practical application of lithium metal anodes (LMAs). In this work, a hollow nanostructure, based on hierarchical MoS2 coated hollow carbon particles preloaded with sulfur (C@MoS2 /S), was designed to modify the LMA. The C@MoS2 hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. More importantly, the encapsulated sulfur could gradually release lithium polysulfides during the Li plating/stripping, acting as an effective additive to promote the formation of a mosaic solid electrolyte interphase layer embedded with crystalline hybrid lithium-based components. These two factors together effectively suppress the growth of Li dendrites. The as-modified LMA shows a high Coulombic efficiency of 98 % over 500 cycles at the current density of 1 mA cm-2 . When matched with a LiFePO4 cathode, the assembled full cell displays a highly improved cycle life of 300 cycles, implying the feasibility of the proposed LMA.

Hierarchical FeCoS2 -CoS2 double-shelled nanotubes have been rationally designed and constructed for efficient photocatalytic CO2 reduction under visible light. The synthetic strategy, engaging the two-step cation-exchange reactions, precisely integrates two metal sulfides into a double-shelled tubular heterostructure with both of the shells assembled from ultrathin two-dimensional (2D) nanosheets. Benefiting from the distinctive structure and composition, the FeCoS2 -CoS2 hybrid can reduce bulk-to-surface diffusion length of photoexcited charge carriers to facilitate their separation. Furthermore, this hybrid structure can expose abundant active sites for enhancing CO2 adsorption and surface-dependent redox reactions, and harvest incident solar irradiation more efficiently by light scattering in the complex interior. As a result, these hierarchical FeCoS2 -CoS2 double-shelled nanotubes exhibit superior activity and high stability for photosensitized deoxygenative CO2 reduction, affording a high CO-generating rate of 28.1 μmol h-1 (per 0.5 mg of catalyst). Ministry of Education (MOE) National Research Foundation (NRF) Accepted version X. W. L. acknowledges the funding support from the National Research Foundation (NRF) of Singapore via the NRF investigatorship (NRF-NRFI2016-04), and the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2017-T2-2-003) and Tier-1 grant (RG116/18).

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient sodium storage. However, the construction of hybrid structures with decent physical/electrochemical properties is still challenging. Now, the elaborate design and synthesis of hierarchical nanoboxes composed of three-layered Cu2 S@carbon@MoS2 as anode materials for sodium-ion batteries is reported. Through a facile multistep template-engaged strategy, ultrathin MoS2 nanosheets are grown on nitrogen-doped carbon-coated Cu2 S nanoboxes to realize the Cu2 S@carbon@MoS2 configuration. The design shortens the diffusion path of electrons/Na+ ions, accommodates the volume change of electrodes during cycling, enhances the electric conductivity of the hybrids, and offers abundant active sites for sodium uptake. By virtue of these advantages, these three-layered Cu2 S@carbon@MoS2 hierarchical nanoboxes show excellent electrochemical properties in terms of decent rate capability and stable cycle life. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Photocatalysts with well-designed compositions and structures are desirable for achieving highly efficient solar-to-chemical energy conversion. Heterostructured semiconductor photocatalysts with advanced hollow structures possess beneficial features for promoting the activity towards photocatalytic reactions. Here we develop a facile synthetic strategy for the fabrication of Fe2TiO5-TiO2 nanocages (NCs) as anode materials in photoelectrochemical (PEC) water splitting cells. A hydrothermal reaction is performed to transform MIL-125(Ti) nanodisks (NDs) to Ti-Fe-O NCs, which are further converted to Fe2TiO5-TiO2 NCs through a post annealing process. Owing to the compositional and structural advantages, the heterostructured Fe2TiO5-TiO2 NCs show enhanced performance for PEC water oxidation compared with TiO2 NDs, Fe2TiO5 nanoparticles (NPs) and Fe2TiO5-TiO2 NPs. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF)Tier-2 grant (MOE2019-T2-2-049).

Highlights from the Science family of journals

High–energy density lithium (Li) metal batteries (LMBs) are promising for energy storage applications but suffer from uncontrollable electrolyte degradation and the consequently formed unstable solid-electrolyte interphase (SEI). In this study, we designed self-assembled monolayers (SAMs) with high-density and long-range–ordered polar carboxyl groups linked to an aluminum oxide–coated separator to provide strong dipole moments, thus offering excess electrons to accelerate the degradation dynamics of carbon-fluorine bond cleavage in Li bis(trifluoromethanesulfonyl)imide. Hence, an SEI with enriched lithium fluoride (LiF) nanocrystals is generated, facilitating rapid Li + transfer and suppressing dendritic Li growth. In particular, the SAMs endow the full cells with substantially enhanced cyclability under high cathode loading, limited Li excess, and lean electrolyte conditions. As such, our work extends the long-established SAMs technology into a platform to control electrolyte degradation and SEI formation toward LMBs with ultralong life spans.

The development of efficient and cost-effective electrocatalysts toward the oxygen evolution reaction (OER) is highly desirable for clean energy and fuel conversion. Herein, the facile preparation of Ni single atoms embedded hollow S/N-doped carbon macroporous fibers (Ni SAs@S/N-CMF) as efficient catalysts for OER through pyrolysis of designed CdS-NiSx/polyacrylonitrile composite fibers is reported. Specifically, CdS provides the sulfur source for the doping of polyacrylonitrile-derived carbon matrix and simultaneously creates the hollow macroporous structure, while NiSx is first reduced to nanoparticles and finally evolves into single Ni atoms through the atom migration-trapping strategy. Benefiting from the abundantly exposed single Ni atoms and hollow macroporous structure, the resultant Ni SAs@S/N-CMF electrocatalysts deliver outstanding activity and stability for OER. Specifically, it needs an overpotential of 285 mV to achieve the benchmark current density of 10 mA cm−2 with a small Tafel slope of 50.8 mV dec−1. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2019-T2-2-049). X.J.G. acknowledges the funding support from the National Natural Science Foundation of China (22162019), and the Science and Technology Projects of Inner Mongolia Autonomous Region (2021GG0195).

The practical application of Zn-metal anodes (ZMAs) is mainly impeded by the limited lifespan and low Coulombic efficiency (CE) resulting from the Zn dendrite growth and side reactions. Herein, a 3D multifunctional host consisting of N-doped carbon fibers embedded with Cu nanoboxes (denoted as Cu NBs@NCFs) is rationally designed and developed for stable ZMAs. The 3D macroporous configuration and hollow structure can lower the local current density and alleviate the large volume change during the repeated cycling processes. Furthermore, zincophilic Cu and in-situ-formed Cu-Zn alloy can act as homogeneous nucleation sites to minimize the Zn nucleation overpotential, further guiding uniform and dense Zn deposition. As a result, this Cu NBs@NCFs host exhibits high CE of Zn plating/stripping for 1000 cycles. The Cu NBs@NCFs-Zn electrode shows low voltage hysteresis and prolonged cycling life (450 h) with dendrite-free behaviors. As a proof-of-concept demonstration, a Zn-ion full cell is fabricated based on this Cu NBs@NCFs-Zn anode, which demonstrates decent rate capability and improved cycling performance. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-1 grant (RG3/20) and Tier-2 grant (MOE2019-T2-2-049).

Trapping the active sites on the exterior surface of hollow supports can reduce mass transfer resistance and enhance atomic utilization. Herein, we report a facile chemical vapor deposition strategy to synthesize single-Ni atoms decorated hollow S/N-doped football-like carbon spheres (Ni SAs@S/N-FCS). Specifically, the CdS@3-aminophenol/formaldehyde is carbonized into S/N-FCS. The gas-migrated Ni species are anchored on the surface of S/N-FCS simultaneously, yielding Ni SAs@S/N-FCS. The obtained catalyst exhibits outstanding performance for alkaline oxygen evolution reaction (OER) with an overpotential of 249 mV at 10 mA cm−2, a small Tafel slope of 56.5 mV dec−1, and ultra-long stability up to 166 hours without obvious fading. Moreover, the potential-driven dynamic behaviors of Ni-N4 sites and the contribution of the S dopant at different locations in the matrix to the OER activity are revealed by the operando X-ray absorption spectroscopy and theoretical calculations, respectively. Ministry of Education (MOE) Submitted/Accepted version X.W.L. acknowledges the funding support from the Ministry of Education of Singapore through the Academic Research Fund (AcRF) Tier-2 grant (MOE2019-T2-2-049). X.J.G. acknowledges the funding support from the National Natural Science Foundation of China (22162019), and the Science and Technology Projects of Inner Mongolia Autonomous Region (2021GG0195).

We developed a three-dimensional hybrid fiber host consisting of interconnected N-doped hollow carbon spheres embedded with Sn nanoparticles (denoted as Sn@NHCF) for Zn metal anodes in high-performance Zn metal batteries. Experimental observations and density functional theory calculation reveal that the zincophilic Sn nanoparticles and N-doped carbons enable the homogeneous Zn deposition on the interior and exterior surfaces of the hollow fibers. Moreover, the hierarchical hollow fiber network effectively reduces the structural stress during the plating/stripping process. As a result, the developed Sn@NHCF host exhibits remarkable electrochemical properties in terms of high Coulombic efficiency, low voltage hysteresis, and prolonged cycling stability without dendrite formation. Moreover, a full cell based on the designed Sn@NHCF-Zn composite anode and a V2O5 cathode demonstrates superior rate capability and stable cycle life. This work provides a new strategy for the design of dendrite-free Zn anodes for practical applications. Published version L.Y. acknowledges the financial support from the National Natural Science Foundation of China (grant no. 51902016) and Fundamental Research Funds for the Central Universities (grant no. buctrc201829). N.W.L. acknowledges the financial support from the National Natural Science Foundation of China (grant no. 21975015) and Fundamental Research Funds for the Central Universities (grant no. buctrc201904).

The development of MnO

Uncontrolled growth of Zn dendrites and side reactions are the major restrictions for the commercialization of Zn metal anodes. Herein, we develop a TiOx /Zn/N-doped carbon inverse opal (denoted as TZNC IO) host to regulate the Zn deposition. Amorphous TiOx and Zn/N-doped carbon can serve as the zincophilic nucleation sites to prevent the parasitic reactions. More importantly, the highly ordered IO host homogenizes the local current density and electric field to stabilize Zn deposition. Furthermore, the three-dimensional open networks could regulate Zn ion flux to enable stable cycling performance at large current densities. Owing to the abundant zincophilic sites and the open structure, granular Zn deposits could be realized. As expected, the TZNC IO host guarantees the steady Zn plating/stripping with a long-term stability over 450 h at the current density of 1 mA cm-2 . As a proof-of-concept demonstration, a TZNC@Zn||V2 O5 full cell shows long lifespan over 2000 cycles at 5.0 A g-1 . This work was supported by the National Natural Science Foundation of China (Grant No.51902016 and 21975015), the Fundamental Research Funds for the Central Universities (Grant No. buctrc201829 and buctrc201904).