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Abstract Oxygen evolution reaction (OER) contributes to the main overpotential during water splitting. Developing efficient, nonprecious OER electrocatalysts is vital for sustainable fuels. Herein, nickel iron boride nanosheets coupled with reduced graphene oxide (rGO) has been developed as efficient OER electrocatalyst. The two-dimensional hybrid affords high surface area and abundant active sites for catalytic reaction. The rGO substrate improves the charge transfer. The ternary Ni-Fe-B supplies synergism for OER. As a result, the Ni-Fe-B/rGO exhibits excellent OER performances with low overpotential of 265 mV at 10 mA cm−2, as well as excellent catalytic stability, making it the promising candidate for OER application. Graphical abstract Nickel iron boride nanosheets coupled with rGO has been firstly developed as efficient OER electrocatalyst, which delivers excellent OER activity that is superior to most of previously meal borides. fx1 Highlights • Ni-Fe-B nanosheets are closely coupled with rGO. • Structural advantages and rGO assure fast kinetics and large accessible sites. • Excellent OER catalytic activity and stability are obtained. [ABSTRACT FROM AUTHOR]

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]

Searching active and cost-effective bifunctional electrocatalysts for overall water splitting is a vital but challenging task towards clean and sustainable energy sources. Here, mixed metal phosphides of Ni 2 P CoP anchored on N-doped reduced graphene oxide (NiCoP/N-rGO) as efficient and earth-abundant electrocatalysts for water splitting are reported. The large active sites, synergism, and hybridization with N-doped rGO endow NiCoP/N-rGO electrocatalyst with outstanding oxygen evolution reaction activity that is better than benchmark RuO 2 in alkaline electrolyte, as well as active hydrogen evolution reaction in acidic, neutral, and alkaline solution. NiCoP/N-rGO has further been employed as both anode and cathode in a two-electrode alkaline water electrolyzer towards overall water splitting, exhibiting advanced electrochemical performances with a low cell voltage of 1.57 V at a current density of 20 mA cm −2 . Moreover, the overall water splitting in this two-electrode electrolyzer can be driven by a single-cell AA battery (nominal voltage of 1.5 V), making NiCoP/N-rGO as the promising efficient cost-effective catalysts for water electrolysis. [ABSTRACT FROM AUTHOR]

MoS 2 is recognized as competitive low-cost and efficient electrocatalyst for water electrolysis application, and its catalytic activity needs further improving. Nitrogen doped MoS 2 nanosheets assembled flowers have been firstly synthesized as hydrogen evolution reaction (HER) catalyst. N-doping is determined by XPS characterization, which achieves boosting effect on HER activity. Edge terminated feature supplies exposed active sites for catalytic reaction. N-MoS 2 exhibits excellent HER activity with a low overpotential of 114 mV to afford a current density of 10 mA cm −2 and high stability, making it good candidate as advanced HER electrocatalyst. [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]

Nano-engineering is an effective strategy to achieve improved catalytic performance. A specific high-performance electrocatalyst of graphene quantum dots doped MoS 2 nanosheets with defect-rich structures and improved electrical conductivity, referred as GQDs-MoS 2 , has been rationally designed and successfully developed through a facile hydrothermal method. XRD, SEM, TEM, and Raman techniques are employed to reveal the formation and the structural features. The doping of GQDs into MoS 2 nanosheets plays the key role in enhancing the catalytic activity by creating abundant defect sites both in the edge plane and the basal plane, as well as enhancing the electrical conductivity. Endowed with this, the sample delivers remarkably improved catalytic properties for electrochemical hydrogen evolution reaction, including the large cathodic current (10 mA cm −2 at a small overpotential of 200 mV and 74 mA cm −2 at a small overpotential of 300 mV) and low onset potential (140 mV). [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]