Interlayer-Confined NiFe Dual Atoms within MoS2 Electrocatalyst for Ultra-Efficient Acidic Overall Water Splitting

Confining dual atoms (DAs) within the van der Waals gap of 2D layered materials is expected to expedite the kinetic and energetic strength in catalytic process, yet is a huge challenge in atomic-scale precise assembling DAs within two adjacent layers in the 2D limit. Here, an ingenious approach is proposed to assemble DAs of Ni and Fe into the interlayer of MoS2 . While inheriting the exceptional merits of diatomic species, this interlayer-confined structure arms itself with confinement effect, displaying the more favorable adsorption strength on the confined metal active center and higher catalytic activity towards acidic water splitting, as verified by intensive research efforts of theoretical calculations and experimental measurements. Moreover, the interlayer-confined structure also renders metal DAs a protective shelter to survive in harsh acidic environment. The findings embodied the confinement effects at the atom level, and interlayer-confined assembling of multiple species highlights a general pathway to advance interlayer-confined DAs catalysts within various 2D materials.

Non-Precious Metal-Doped Carbon Materials Derived From Porphyrin-Based Porous Organic Polymers for Oxygen Reduction Electrocatalysis

The cathodic oxygen reduction reaction (ORR) is important in the development of renewable energy devices, to produce novel and non-precious metal catalysts with high electrocatalytic activity to reduce the consumption of non-renewable platinum (Pt) catalyst. In this work, we developed N-doped and Fe/N dual-doped porous carbons as catalysts for ORR simply by high-temperature pyrolysis of porphyrin-based conjugated microporous polymers (CMPs). By combination of heteroatom doping, highly porous structure and tubular morphology, the as-prepared carbon samples exhibited high electrocatalytic activity with 4-electron transfer mechanism, nearly close to the commercial Pt/C catalyst. In particular, among these samples, the Fe/N-CMP-1000 displayed a higher onset potential (0.95 eV), positive half-wave potential (0.85 eV) and limiting current density value (5.1 mA cm^-2 ) as well as good durability and better methanol tolerance contrasting with Pt/C catalyst, suggesting that the as-prepared metal-free catalysts from porphyrin-based CMPs show great potential for ORR.

Benzoxazine Porous Organic Polymer as an Efficient Solid-Phase Extraction Adsorbent for the Enrichment of Chlorophenols from Water and Honey Samples

Porous organic polymers have gained great research interest in the field of adsorption. A benzoxazine porous organic polymer (BoxPOP) constructed from p-phenylenediamine, 1,3,5-trihydroxybenzene and paraformaldehyde was fabricated and explored as an adsorbent for solid-phase extraction (SPE) of four chlorophenols from water and honey samples. Under the optimized SPE conditions, the response linearity for the analysis of the SPE extract of the chlorophenols by high performance liquid chromatography-diode array detector was observed in the range of 0.2-40.0 ng mL-1 for water samples and 5.0-400.0 ng g-1 for honey samples. The method detection limits of the analytes were 0.06-0.08 ng mL-1 for water samples and 1.5-2.0 ng g-1 for honey samples. The recoveries of the analytes from fortified water and honey samples ranged from 84.8 to 119.0% with the relative standard deviations below 8.4%. The results indicate that the prepared BoxPOP is an effective adsorbent for the chlorophenols. The established method provides an alternative approach for the determination of chlorophenols in real samples.

Two-dimensional conjugated microporous polymer films: fabrication strategies and potential applications

This review describes the latest advances in the preparation and application of two-dimensional conjugated microporous polymers, as well as the future research directions of this field.

Mechanism and activity of the oxygen reduction reaction on WTe2 transition metal dichalcogenide with Te vacancy

WTe2 transition metal dichalcogenide is a promising candidate for the cathode of proton-exchange membrane fuel cells. In this paper, we investigated the mechanism and activity of the oxygen reduction reaction on the monolayer of the WTe2 transition metal dichalcogenide with Te vacancy denoted as WTed 2. By using density functional theory calculations, we studied the reaction intermediates on the surface of WTed 2. The Gibbs free energy was calculated to clarify the thermodynamic properties of the reaction. We discovered that the ORR mechanisms are more favorable outside than inside the vacancy. The ORR activity was found to be comparable to that of the well-known transition metal electro-catalysts.

MoS2 -Carbon Nanotube Porous 3 D Network for Enhanced Oxygen Reduction Reaction

Future generation power requirement triggers the increasing search for electrocatalysts towards oxygen reduction, which is the pivotal part to enhance the activity of metal-air batteries and fuel cells. The present article reports a novel 3 D composite structure weaving 1 D carbon nanotubes (CNT) and 2 D MoS₂ nanosheets. The MoS₂ -CNT composite exhibits excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline environment. Measurements show better methanol immunity and higher durability than Pt/C, which is considered the state-of-the-art catalyst for ORR. Experimental results suggest that the hybridization of 1 D functionalized multiwalled CNTs (MWCNTs) and exfoliated 2 D MoS₂ nanosheet results significant synergistic effect, which greatly promotes the ORR activity. This work presents a new avenue to rationally design a 3 D porous composite out of 1 D and 2 D interlaced components and demonstrate appreciable electrochemical performance of the materials towards ORR activity for fuel cells as well as metal-air batteries.

Facile Synthesis of Composition-Controlled Graphene-Supported PtPd Alloy Nanocatalysts and Their Applications in Methanol Electro-Oxidation and Lithium-Oxygen Batteries

A new and simple approach is reported for the synthesis of uniformly dispersed PtPd alloy nanocatalysts supported on graphene nanoplatelets (GNPs) (PtPd-GNPs) through the introduction of bifunctional materials, which can modify the GNP surface and simultaneously reduce metal ions. With the use of poly(4-styrenesulfonic acid), poly(vinyl pyrrolidone), poly(diallyldimethylammonium chloride), and poly(vinyl alcohol) as bifunctional materials, PtPd-GNPs can be produced through a procedure that is far simpler than previously reported methods. The as-prepared nanocrystals on GNPs clearly exhibit uniform PtPd alloy structures of around 2 nm in size, which are strongly anchored and well distributed on the GNP sheets. The Pt/Pd atomic ratio and loading density of the nanocrystals on the GNPs are controlled easily by changing the metal precursor feed ratio and the mass ratio of GNP to the metal precursor, respectively. As a result of the synergism between Pt and Pd, the as-prepared PtPd-GNPs exhibit markedly enhanced electrocatalytic performance during methanol electro-oxidation compared with monometallic Pt-GNP or commercially available Pt/C. Furthermore, the PtPd-GNP nanocatalysts also show greatly enhanced catalytic activity toward the oxygen reduction/evolution reaction in a lithium-oxygen (Li-O₂ ) process, resulting in greatly improved cycling stability of a Li-O₂ battery.