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Highlights: [•] FePt alloy nanoparticles anchored RGO composites are successfully synthesized. [•] The alloying of Fe with Pt is demonstrated with XRD and elemental maps. [•] FePt/RGO show enhanced catalytic activity on FA/methanol oxidation than Pt/RGO. [•] FePt/RGO also exhibit improved tolerance to CO poisoning than Pt/RGO. [Copyright &y& Elsevier]

Vanadium oxides are potential anode materials for sodium-ion batteries, however, their application is limited for their rate capability and cycle life. Herein, hollow spheres of Co-doped V 2 O 3 enveloped in N-doped carbon (Co-V 2 O 3 @NC) are prepared through a hydrothermal step with the following sintering process. The hollow spherical structure supplies short distance and large area for fast ion transfer kinetics, which also provides voids to ease the volume expansion. The strong coupling between Co-V 2 O 3 nanoparticles and carbon layer constitutes a solid structure that enhances the conductivity and keeps electrode integrity. Co-doping introduces plenty of active sites for surface capacitance behavior and accelerates charge transfer. On account of the benefits, Co-V 2 O 3 @NC exhibits excellent Na+ storage properties as anode, including high capacity of 338.5 mAh g−1 at 0.1 A g−1, stable cycling capability of 240 mAh g−1 after 1000 cycles at 1 A g−1, and excellent rate performance. This work describes the importance of constructing specific structured materials for advanced anodes. [Display omitted] • Hollow spheres of Co-doped V 2 O 3 enveloped in N-doped carbon are prepared. • Hollow structure accelerates ion transfer kinetics and buffers volume expansion. • Co-doping provides sites for surface-controlled sodium storage. • Carbon coating improves conductivity and benefits electrode integrity. • High-performance sodium storage performances are acquired. [ABSTRACT FROM AUTHOR]

Integrating heterogeneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts into compatible composite catalysts with specific interfaces and structures holds great promise for the development of efficient bifunctional catalysts for overall water splitting. Herein, heterogeneous MoS 2 -Ni(OH) 2 catalyst supported by Ni foam (MoS 2 @Ni(OH) 2 /NF) is developed, in which the Ni(OH) 2 nanorod array is grafted with MoS 2 nanosheets. The hierarchical 1D/2D structures benefit not only the exposure of catalytic site but also the facilitated charge transfer. The heterointerfaces allow the synergism of electric structure modulation for improved catalytic activity and kinetics towards HER, OER, and overall water splitting. MoS 2 @Ni(OH) 2 /NF achieves a current density of 10 mA cm−2 at low overpotentials of 134 and 233 mV for HER and OER in 1 M KOH, respectively. Moreover, a cell voltage as low as 1.46 V is obtained to afford 10 mA cm−2 in a tow-electrode electrolyzer using MoS 2 @Ni(OH) 2 /NF as bifunctional catalysts, assuring it superior to most of the reported noble-metal-free bifunctional electrocatalysts. Such heterogeneous design of composite catalyst should shed light on the exploration of functional materials for energy applications. Image 1 • MoS 2 @Ni(OH) 2 /NF is developed as bifunctional catalyst for water splitting. • MoS 2 nanosheets are decorated on Ni(OH) 2 nanorod array. • Specific structure improves charge transfer and active sites. • Synergism facilitates reaction kinetics and activity. • Superior HER, OER, and overall water splitting activities are obtained. [ABSTRACT FROM AUTHOR]

Exploring electrocatalysts which efficiently perform the hydrogen evolution reaction (HER) catalytic activity over wide pH range is greatly important for water splitting, however, remains enormous challenge. Herein, the host catalyst of CoP nanoarray on carbon cloth is co-doped with the guest elements of vanadium and nitrogen to acquire tuned electronic characteristics and additional active sites for improved HER activity. The electrochemical measurements show that the as-obtained V, N-CoP is endowed with smaller overpotentials and Tafel slopes than V-CoP and CoP. Impressively, V, N-CoP only needs low overpotentials of 57, 146, and 81 mV at 10 mA cm−2 in 1 M KOH, 1 M phosphate buffer, and 0.5 M H 2 SO 4 , respectively. This study sets a blueprint for developing pH-universal HER electrocatalysts via metal and nonmetal elements co-doping engineering. Image 1 • V and N are co-doped into CoP nanoleaf array for improved HER. • The co-doping induces the subtle lattice distortion as additional active sites. • The co-doping leads to improved catalytic kinetics and charge transfer. • Excellent HER performances are obtained in acid, PBS buffer, and alkali. [ABSTRACT FROM AUTHOR]

Abstract MoS 2 shows promising potential in the application of lithium ion batteries (LIBs) or sodium ion batteries (SIBs), however, suffering from the sluggish kinetics and terrible volume expansion. Here we fabricate interlayer-expanded VMo 2 S 4 nanosheets onto RGO and exhibit excellent electrochemical properties for lithium and sodium storage. The 2D nature and interlayer-expanded feature assure the shortened ion transfer path and improved diffusion kinetics. RGO substrates enhance the electric conductivity and preserve the material integrity. Based on such benefits, the present sample serves as advanced anode for both LIBs and SIBs, delivering reversible capacities of 1081 mAh g−1 for LIBs and 254 mAh g−1 for SIBs after 200 cycles at 1 A g−1. Graphical abstract Image 1 Highlights • Interlayer-expanded VMo 2 S 4 nanosheets on RGO are developed. • V dopants induce enlarged interlayer and synergism between V and Mo. • RGO improves conductivity and buffers the volume variation. • 2D feature shortens ion diffusion path. • High and fast lithium/sodium storage are obtained. [ABSTRACT FROM AUTHOR]

Heterostructure fabrication is believed to acquire promoted charge transfer and improved surface storage contribution, thus obtaining high-performance anodes for sodium-ion batteries. Herein, the simultaneous phosphatization and selenization of polydopamine functionalized ZIF-67 is adopted to engineer N-doped carbon coated Co(PO 3) 2 /CoSe 2 heterostructure. The hetero-interface with plenty of surface sites is activated with large surface reaction and fast sodium ion transport dynamics. The multiphase synergism and carbon coating layer assure high conductivity and structural stability. The designed sample delivers impressive anode performance, exhibiting a high sodium storage capacity of 333.4 mAh g−1 at 0.1 A g−1 and 192.7 mAh g−1 after 1000 cycles at 2 A g−1. This simple and reasonable method can be utilized to construct other transition metal based heterostructures with multiphase synergism for the application of advanced anodes. [Display omitted] • N-doped carbon coated Co(PO 3) 2 /CoSe 2 heterostructure is prepared. • Heterostrucrue favors surface-controlled pseudocapacitive sodium storage. • N-doped carbon shell enhances conductivity and keeps electrode integrity. • Multiphase synergism benefits electrochemical kinetics and structure stability • Large/fast sodium storage properties with excellent stability are obtained. [ABSTRACT FROM AUTHOR]

Transition metal sulfides have attracted intensive interests as cost-effective catalysts for water electrolysis. However, demands for their active catalytic activity towards hydrogen evolution reaction (HER), and especially oxygen evolution reaction (OER) are still urgently needed and challenging. To address this issue, we rationally select B, N co-doped graphene nanotubes (BN-CNT) as active substrate to support CoMoS 3.13 nanosheets to fabricate bifunctional catalyst for overall water electrolysis. The present contribution indicates that, doped N and B species can serve as active sites to improve the HER and OER activity of transition metal sulfides. Moreover, BN-CNT substrate not only assures the edge terminated texture of CoMoS 3.13 nanosheets for more active sites, but also acts as “highway” to accelerate the charge transfer for enhanced reaction kinetics. Therefore, remarkably enhanced HER and OER catalytic activities are obtained from the hybrid catalyst, including decreased overpotetnial, increased catalytic current density, improved reaction kinetics, and superior stable durability. We believed that BN-CNT could be further used to composite with other metal chalcogenides, hydroxides, or phosphides as high-performance electrocatalysts for applications in sustainable energy conversion systems. [ABSTRACT FROM AUTHOR]

Rational design and constructing advanced materials with intriguing nanostructures towards highly efficient and sustainable energy conversion and storage have received focused research efforts, but exploring effective strategies to accomplish this mission is still challenging. Aiming at this goal, we construct MoS 2 nanosheets on Fe 3 O 4 nanospheres via a SiO 2 shell assisted sacrifice template method for the first time. The shell-core structured MoS 2 @Fe 3 O 4 catalyst is well characterized by XRD, Raman, TEM, SEM, and XPS techniques. SEM and TEM show that MoS 2 nanosheets possess edge exposed feature and defect-rich structure, assuring the maximum active sites for electrochemical hydrogen evolution reaction (HER). Raman characterization reveals the chemical coupling between MoS 2 and Fe 3 O 4 , indicating the formation of MoS 2 @Fe 3 O 4 heterostructure at the shell-core interface. High-resolution TEM (HRTEM) shows abundant defects at the heterostructures, which supplies more catalytic sites. The improved catalytic sites are proved by electrochemical capacitance measurements, and the enhanced catalytic activity over each site is also probed. Therefore, MoS 2 @Fe 3 O 4 exhibits remarkably enhanced catalytic activity for water splitting due to the above mentioned benefits. [ABSTRACT FROM AUTHOR]

• Heterogeneous Co@CoO encapsulated in P, N co-doped carbon fibers is prepared. • Synergism between Co and CoO is beneficial to improve OER. • PNC fiber benefits charge transfer and catalysis stability. • Low overpotentials of 289 (KOH) and 371 (PBS) mV at 10 mA cm−2 for OER. Heterostructured materials favoring synergism, efficient charge transfer, and abundant active sites have aroused enormous interests for water electrolysis. Here heterogeneous Co@CoO encapsulated in P, N co-doped carbon nanofibers supported on carbon cloth (Co@CoO-PNC/CC) has been prepared to pursue attractive synergism for the application of pH-tolerant catalyst for oxygen evolution reaction (OER) in both alkaline and neutral solutions. The prepared Co@CoO-PNC/CC exhibits advanced OER performances, generating a current density of 10 mA cm−2 at overpotential of 289 mV in alkaline media and 371 mV in neutral media. The high OER activity can be assigned to the synergistic effect of abundant active sites and enhanced charge transfer between Co and CoO, as well as the specific P, N co-doped carbon nanofiber architecture. [ABSTRACT FROM AUTHOR]

• S, N co-doped carbon nanosheets are prepared as SIBs anode. • S, N co-doping endows enlarged interlamellar spacing and defective active sites for improved sodium storage. • S, N co-doping improves Na+ diffusion coefficient. • High capacity of 270 mAh g−1 is obtained at 0.1 A g−1 after 100 cycles. • Capacity of 100 mAh g−1 is achieved at high rate of 1 A g−1 after long-term 1000 cycles. Heteroatom doping into specific nanostructure is believed as the leading solution for developing the advanced carbon materials for sodium ion batteries (SIBs), however, the preparation and understanding of heteroatoms co-doped carbon anodes are still challenging. Herein, the sulfur and nitrogen co-doped (weight content of 15.64% for N and 3.1% for S) carbon nanosheets (SNC) are prepared by treating nitrogen-rich carbon nanosheets with sublimation sulfur. The S, N co-doping is responsible for the enlarged interlamellar spacing of 0.38 nm and abundant defect-introduced active sites. These structure features combined with the advantage of nanosheet are significant for activating sodium ion storage properties, endowing SNC with high Na+ storage capacity of 270 mAh g−1 at 0.1 A g−1 and 100 mAh g−1 at 1 A g−1 after 1000 cycles. More importantly, the kinetic analysis is carried out to illustrate that S, N co-doping can improve the Na+ diffusion coefficient in carbon anode and enhance the ion storage. This work deepens the understanding on the boosting effect of heteroatoms dual-doping for the sodium ion storage of carbon materials, which conduces to development of advanced heteroatom doped carbon anodes for SIBs. [ABSTRACT FROM AUTHOR]

• P-doped Ni 3 S 2 -NiS nanorod arrays are developed. • P-doping activates the intrinsic catalysis activity. • P-doping improves charge transfer and catalysis kinetics. • P-doping induces numerous active sites. • High bifunctionality of 1.51 V at 10 mA cm−2 for overall water splitting. Preparing P-doped hybrid Ni 3 S 2 -NiS nanorod arrays as efficient dualfunctional catalysts for overall water electrolysis in alkaline media ga1 Exploring efficient non-metal catalysts to simultaneously drive hydrogen evolution and oxygen evolution is significantly important but challenging for practical overall water electrolysis. Herein, anionic doping engineering is adopted to develop phosphorus-doped hybrid Ni 3 S 2 -NiS nanorod arrays as efficient dualfunctional catalysts in alkaline media. P-doping and hetero-interface engineering induce improved active sites in the catalysis. Nanorod arrays structure is beneficial for charge and mass transfer, and P-doping promotes the conductivity and intrinsic catalysis activity. Serving as bifunctional catalyst, the present sample exhibits outstanding activities, with low overpotentials of 141 mV and 178 mV at current density of 10 mA cm−2 for cathodic hydrogen and anodic oxygen evolution, respectively. In a two-electrode cell with P-doped Ni 3 S 2 -NiS as bifunctional electrode, the active overall water splitting activity (cell voltage of 1.51 V at 10 mA cm−2 and 1.67 V at 100 mA cm−2) and good stability are obtained. [ABSTRACT FROM AUTHOR]

Developing advanced electrode materials for sodium storage is hindered by the sluggish Na+ diffusion kinetics and terrible structure damage. Pseudocapacitance is believed as a promising solution to supply fast, large and stable sodium storage via surface-controlled behavior. Herein, a hybrid material approach is implemented to pursue pseudocapacitance contributed sodium storage by constructing nitrogen-doped graphene nanosheets packed SnP 2 O 7 particles. The rationally selected components and specific structure also provide advantages for electrolyte penetration and Na+ diffusion, fast charge transfer, and structure stability. Hence, the developed composite delivers anode performances for sodium storage with high capacity of 423 mAh g−1 at 0.1 A g−1, good rate performance of 206 mAh g−1 at 2 A g−1, and stable cyclic property (retention rate of ∼95% after 1000 cycles at 1 A g−1). Pseudocapacitance contribution is vital for the composite electrode, especially at high rate, dedicating a percentage as high as 89% to the total capacity at a sweep rate of 1 mV s−1. This work demonstrates the promising potential of compositing graphene and conversion reaction material as pseudocapacitive electrode for sodium ion batteries. • N-doped graphene wrapped SnP 2 O 7 particles is prepared as SIBs anode. • Composition and structure characteristics benefit sodium storage. • Pseudocapacitive dominated sodium storage is acquired. • Large/fast sodium storage with excellent stability is obtained. [ABSTRACT FROM AUTHOR]

Developing novel catalysts with high efficiency and low cost for electrochemical hydrogen production is of great significance for sustainable energy applications. Herein, we present the exploratory research on nickel foam supported heterostructures of NiCo hydrogen carbonate (Ni 0.6 Co 0.4 (HCO 3) 2) with Pt nanoparticles on the surface for alkaline water hydrogen evolution reaction (HER). The heterogeneous engineering ensures effective synergism of moderate hydrogen adsorption energy, accelerated catalysis kinetics, improved active sites, and enhanced charge transfer, thus inducing excellent HER activity (56 mV at 10 mA cm−2 for geometric area and 15 mV at 10 mA cm−2 for electrochemical surface area) and stable durability. Notably, the mass activity of Pt in Pt–Ni 0.6 Co 0.4 (HCO 3) 2 is even higher than that of Pt/C. This study provides new insights into developing high-efficiency catalysts for hydrogen electrocatalysis, which also demonstrates that hydrogen carbonates are promising alternatives for electrochemical water splitting in addition to the widely focused transition metal hydroxides and oxides. • Ni 0.6 Co 0.4 (HCO 3) 2 is firstly hybridized with Pt for improved HER. • The electronic interaction moderates the hydrogen adsorption energy on Pt. • The intrinsic HER activity is activated. • Improved active sites density and enhanced charge transfer are acquired. • The mass activity of Pt in composite catalyst is higher than that of Pt/C. [ABSTRACT FROM AUTHOR]