Intercalated and Surface-Adsorbed Phosphate Anions in NiFe Layered Double-Hydroxide Catalysts Synergistically Enhancing Oxygen Evolution Reaction Activity.

The oxygen evolution reaction (OER), a crucial semireaction in water electrolysis and rechargeable metal-air batteries, is vital for carbon neutrality. Hindered by a slow proton-coupled electron transfer, an efficient catalyst activating the formation of an O-H bond is essential. Here, we proposed a straightforward one-step hydrothermal procedure for fabricating PO43--modified NiFe layered double-hydroxide (NiFe LDH) catalysts and investigated the role of PO43- anions in enhancing OER. Phosphate amounts can efficiently regulate LDH morphology, crystallinity, composition, and electronic configuration. The optimized sample showed a low overpotential of 267 mV at 10 mA cm-2. Density functional theory calculations revealed that intercalated and surface-adsorbed PO43- anions in NiFe LDH reduced the Gibbs free energy in the rate-determining step of *OOH formation, balancing oxygen-containing intermediate adsorption/dissociation and promoting the OER. Intercalated phosphate ions accelerated precatalyst dehydrogenation kinetics, leading to a rapid reconstruction into active NiFe oxyhydroxide species. Surface-adsorbed PO43- interacted favorably with adsorbed *OOH on the active Ni sites, stabilizing *OOH. Overall, the synergistic effects of intercalated and surface-adsorbed PO43- anions significantly contributed to enhanced OER activity. Achieving optimal catalytic activity requires a delicate equilibrium between thermodynamic and kinetic factors by meticulously regulating the quantity of introduced PO43- ions. This endeavor will facilitate a deeper comprehension of the influence of anions in electrocatalysis for OER.

Partially cross-linked carbon nitride with unimpeded charge transfer between different chains for boosting photocatalytic hydrogen production.

A heptazine-based, partially cross-linked carbon nitride (PC-CN) was successfully prepared via a solid-chloride-salt-assisted polycondensation method. The cross-linking favors the charge transport between different chains, thus dramatically boosting the photocatalytic hydrogen evolution activity of PC-CN, up to 29.3 times that of traditional 1D-CN.

Plasmonic enhanced photocatalytic activity of Ag/TiO2 tube-in-tube fibers.

Ag nanoparticle was found to significantly enhance the photocatalytic activity of self-organized TiO2 nanotube structures. Herein, novel Ag/TiO2 tube-in-tube fibers have been prepared by a facile electrospinning technology and calcination process. Employed as the photocatalyst, the composite could efficiently catalyze the photodegradation of the model organic pollutant, rhodamine B under visible light irradiation, exhibiting a superior photocatalytic activity than the undoped TiO2 tube-in-tube fibers. This enhanced activity has been ascribed to plasmonic characteristics of Ag nanoparticles, which promote the light absorption and charge transfer feasibility. The simple, low-cost and green fabrication route of the composite provides a novel means for preparing similar materials, holding great promise for wider application in the future.

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds.

Mesoporous core-shell structure Ag@SiO2 nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Highly efficient and self-supported 3D carbon nanotube composite electrode for enhanced oxygen reduction reaction.

A binder-free and self-supported 3D carbon nanotube composite electrode with NiFe nanoalloys, N doping and Fe/Ni-N x -C structures was fabricated by a facile method. The strong synergistic effects of multi-components and the unique structural merits of the optimized sample endowed it outstanding oxygen reduction reaction activity with an onset potential of 1.048 V vs. RHE in 0.1 M KOH solution.

Facile Room-Temperature Synthesis of a Highly Active and Robust Single-Crystal Pt Multipod Catalyst for Oxygen Reduction Reaction.

Economical production of highly active and robust Pt catalysts on a large scale is vital to the broad commercialization of polymer electrolyte membrane fuel cells. Here, we report a low-cost, one-pot process for large-scale synthesis of single-crystal Pt multipods with abundant high-index facets, in an aqueous solution without any template or surfactant. A composite consisting of the Pt multipods (40 wt %) and carbon displays a specific activity of 0.242 mA/cm2 and a mass activity of 0.109 A/mg at 0.9 V (versus a reversible hydrogen electrode) for oxygen reduction reaction, corresponding to ∼124% and ∼100% enhancement compared with those of the state-of-the-art commercial Pt/C catalyst (0.108 mA/cm2 and 0.054 A/mg). The single-crystal Pt multipods also show excellent stability when tested for 4500 cycles in a potential range of 0.6-1.1 V and another 2000 cycles in 0-1.2 V. More importantly, the superior performance of the Pt multipods/C catalyst is also demonstrated in a membrane electrode assembly (MEA), achieving a power density of 774 mW/cm2 (1.29 A/cm2) at 0.6 V and a peak power density of ∼1 W/cm2, representing 34% and 20% enhancement compared with those of a MEA based on the state-of-the-art commercial Pt/C catalyst (576 and 834 mW/cm2).

Hollow core-shell structured Ni-Sn@C nanoparticles: a novel electrocatalyst for the hydrogen evolution reaction.

Pt-free electrocatalysts with high activity and low cost are highly pursued for hydrogen production by electrochemically splitting water. Ni-based alloy catalysts are potential candidates for the hydrogen evolution reaction (HER) and have been studied extensively. Here, we synthesized novel hollow core-shell structure Ni-Sn@C nanoparticles (NPs) by sol-gel, chemical vapor deposition, and etching processes. The prepared electrocatalysts with porous hollow carbon layers have a high conductivity and large active area, which exhibit good electrocatalytic activity toward HER. The Tafel slope of ∼35 millivolts per decade measured in acidic solution for Ni-Sn@C NPs is the smallest one to date for the Ni-Sn alloy catalysts, and exceeds those of the most non-noble metal catalysts, indicating a possible Volmer-Heyrovsky reaction mechanism. The synthetic method can be extended to prepare other hollow core-shell structure electrocatalysts for low-temperature fuel cells.

In situ synthesis of porous Fe3O4/C microbelts and their enhanced electrochemical performance for lithium-ion batteries.

The porous Fe3O4/C microbelts (FCBs) were synthesized by simple electrospinning method, combined with carbonization of the precursor microbelts at high temperature in N2 flow. Compared with α-Fe2O3 microbelt, the FCBs show better cyclic performance. The high capacity of 710 mA h g(-1) is still maintained after 50 cycles. The excellent performance of FCBs in lithium-ion batteries can be attributed to the highly stable porous belt structure of FCBs and to the substantial structure carbon matrix surrounded Fe3O4 nanoparticles. The synthesis method is simple, cheap, and green and could be extended to fabricate other carbon composites.

Controllable fabrication of TiO(2) 1D-nano/micro structures: solid, hollow, and tube-in-tube fibers by electrospinning and the photocatalytic performance.

The solid, hollow, and tube-in-tube porous nanofiber structures of TiO(2) are synthesized successfully by a simple non-coaxial electrospinning method without using a complicated coaxial jet head, combined with adjusting the concentration of the TiO(2) precursor and the pinhole diameter of the jet head and by final calcination. The formation mechanisms of different structured TiO(2) fibers are discussed in detail. This method is facile and effective, and easy to scale up. Furthermore, it is a versatile method for constructing tube-in-tube fibers of other metal oxides such as ZrO(2) , SiO(2) , SnO(2) , and In(2) O(3) . The photocatalytic activity of tubular TiO(2) nanofibers for the degradation of 2-chlorophenol and 2,4-dichlorophenol under UV or visible-light irradiation is better than the one of commercial available TiO(2) powder, rutile, and anatase TiO(2) fibers.

Mesoporous ZnS nanospheres: a high activity heterogeneous catalyst for synthesis of 5-substituted 1H-tetrazoles from nitriles and sodium azide.

Mesoporous ZnS nanospheres is a novel heterogeneous catalyst for synthesis of 5-substituted 1H-tetrazoles from various nitriles and sodium azide with excellent catalytic performance.