High-index Facets Research Articles

Nickel–Platinum Alloy Nanocrystallites with High‐Index Facets as Highly Effective Core Catalyst for Lithium–Sulfur Batteries

AbstractElemental sulfur possesses an ultra‐high theoretical specific capacity, while the practical application of sulfur in lithium–sulfur (Li–S) batteries is seriously hindered by the sluggish redox kinetics and serious shuttle effect. Enhancing the catalytic activity of the sulfur host by a rational structural design is the key to address these issues. Herein, for the first time, concave‐nanocubic (CNC) nickel–platinum (Ni–Pt) alloys bounded by high‐index facets (HIFs) are introduced as the core catalyst of sulfur for Li–S batteries. It is demonstrated that the CNC Ni–Pt alloy crystallites dispersed uniformly on graphene exhibit a high electrochemical activity to drive the conversion from intermediate lithium polysulfides to solid discharged products. Benefiting from the accelerated redox kinetics by HIFs, the cathode delivers a low capacity damping of 0.025% per cycle for 1000 cycles at 1 C rate. In particular, a high reversible capacity of 664.9 mAh g−1‐cathode with cathode as active material can be achieved with high sulfur loading (8.8 mg cm−2) and low electrolyte usage (5 µL mgs−1). This study focuses on improving the catalytic activity of sulfur hosts by modulating the exposed facets of core catalyst and provides a new path for the structure optimizing of host materials in Li–S batteries.

Morphology Effect of Bismuth Vanadate on Electrochemical Sensing for the Detection of Paracetamol.

Morphology-control, as a promising and effective strategy, is widely implemented to change surface atomic active sites and thus enhance the intrinsic electrocatalytic activity and selectivity. As a typical n-type semiconductor, a series of bismuth vanadate samples with tunable morphologies of clavate, fusiform, flowered, bulky, and nanoparticles were prepared to investigate the morphology effect. Among all the synthesized samples, the clavate shaped BiVO4 with high index facets of (112), (301), and (200) exhibited reduced extrinsic pseudocapacitance and enhanced redox response, which is beneficial for tackling the sluggish voltammetric response of the traditional nanoparticle on the electrode surface. Benefiting from the large surface-active area and favorable ion diffusion channels, the clavate shaped BiVO4 exhibited the best electrochemical sensing performance for paracetamol with a linear response in the range of 0.5–100 µmol and a low detection limit of 0.2 µmol. The enhanced electrochemical detection of paracetamol by bismuth vanadate nanomaterials with controllable shapes indicates their potential for applications as electrochemical sensors.

Laser-assisted synthesis of Au aerogel with high-index facets for ethanol oxidation

Gold (Au) can be used as an ideal metal electrocatalyst for ethanol and glucose oxidation reactions due to its high performance-to-cost ratio. In this paper, the Au aerogel with high-index facets was synthesized by using the laser ablation in liquid technology, which can improve the electrocatalytic activity of Au. The as-prepared Au aerogel showed excellent mass activity and specific activity toward ethanol oxidation reaction, which are 4.6 times and 2.1 times higher than Au/C, respectively. The 3D porous nature and rich defect of the Au aerogel provide more active sites. In addition, the high-index facets with under-coordinated atoms enhance the adsorption of ethanol and glucose molecules, thus improving the intrinsic catalytic activity of Au aerogel. The effect of high-index facets has also been investigated by density functional theory calculations. Furthermore, the Au aerogels also show good electrocatalytic activity and stability toward glucose oxidation reaction. These results are conducive to promote the practical application of Au in electrocatalysis.

Front Cover Image: Volume 3 Issue 1

Front cover image: High-index facet copper catalysts are more favorable for converting CO2 to high-value multi-carbon products in CO2 electroreduction reduction. In this work, reconstructed Cu nanowires (Cu NWs) featured with (311) high-index facets were obtained through square wave (SW) potential treatments. The FE of C2+ products of SW-Cu NWs is nearly 4 times higher than that of the original Cu NWs under the same condition. The (311) high-index facet can promote the activation of CO2 and the formation of specific *OCCOH intermediate with an accessible energy pathway of dimerization reaction. (DOI: https://doi.org/10.1002/smm2.1082)

High-index facets exposed on metal–organic framework for boosting photocatalytic carbon dioxide reduction

Facets exposed on metal–organic frameworks (MOFs) are considered to be responsible for the efficiency of photocatalytic CO2 conversion. Here, NH2-MIL-125(Ti) with exposed high-index {1 1 2} facets has been investigated in detail for photocatalytic CO2 reduction. Compared with low-index facets, the high-index {1 1 2} facets exhibit superior activity for CO2-to-CO and CO2-to-CH4 conversions, which are 33 and 31 times higher for CO and CH4 productions than the {0 0 1}/{1 1 1} facets. The superior photocatalytic activity is attributed to the large CO2 uptake, efficient photoexcitation, charge separation and migration behaviors of the NH2-MIL-125(Ti) with exposing high-index facets. This study provides an effective strategy to develop MOFs catalysts via facet-engineering for targeted performance.

Relating the orientation of graphene on Cu grains by Euler Angles

The aligned nucleation of graphene domains is vital to the large-area growth of single-crystal graphene, which is mainly determined by the interaction of graphene and underlying substrates. Oriented growth of graphene has been reported on various single-crystal substrates with a distributed orientation. While the relationship of graphene grown on multiple grains in polycrystalline substrates was not clearly understood. Herein, it is found that the orientations of graphene grown on vicinal Cu (111) surface and high-index facets of polycrystalline Cu substrate can be related by Euler angles. The results indicate the affinity of the graphene varied for different orientations of Cu grains. The misorientation angles is consistent on vicinal Cu (111) surface, implying the orientation of graphene is originated from the rotation of underlying Cu grains. It presents important insight into the oriented growth of graphene via multi-seed method, and provides a facile and effective way to forecast orientation of graphene domains.

Pt Concave Nanocubes with High-Index Facets as Electrocatalysts for Glucose Oxidation

The modification of the surface atomic arrangements, especially the exposure of high-index facets, has been considered as a valid strategy to strengthen the catalytic performance of Pt-based nanocrystals. In this article, Pt concave nanocubes (Pt CNCs) with exposed high-index (510) facets are facilely synthesized through a hydrothermal method. Polyvinylpyrrolidone (PVP) and glycine are required for shape control. The mechanism of electrocatalytic oxidation toward glucose by Pt CNCs is fully discussed. The exposed high-index facets consist of abundant low-coordinated atoms (containing edges, steps, and kinks), can supply sufficient active sites for the adsorption of reactants and intermediate species, and thus enhance the catalytic activity in glucose oxidation. By using saturated calomel electrode as the reference electrode, a 1 cm2 platinum sheet as the counter electrode, and glassy carbon electrode (GCE) as the working electrode, the Pt CNC catalyst-decorated GCE exhibits higher peak current densities of 0.25, 0.15, and 0.56 mA cm–2 than those of the commercial Pt/C (10 wt. %)-modified GCE. The Pt CNC catalyst shows a rapid response toward the changes in glucose concentration. The electrocatalytic oxidation of glucose exhibits better performance in neutral and alkaline conditions than in an acidic electrolyte. Above all, the prepared Pt CNC catalysts with high-index (510) facets are expected for their wide use as abiotic catalysts in the electrocatalytic oxidation of glucose.

Electrochemical synthesis of Tetrahexahedral Cu nanocrystals with high-index facets for efficient nitrate electroreduction

Here we successfully synthesized tetrahexahedral copper nanocrystals enclosed with {5 2 0} high-index facets (THH Cu{5 2 0}) by electrochemical square-wave potential method without the utilization of additional capping agents. The THH Cu{5 2 0} exhibited outstanding performance in electroreduction of nitrate to ammonia, achieving a high Faradaic efficiency of 98.3% and a yield rate of up to 9.13 mmol h−1 cm−2 at −0.90 V (vs. RHE) in neutral solution.

P-d Orbital Hybridization Induced by a Monodispersed Ga Site on a Pt3 Mn Nanocatalyst Boosts Ethanol Electrooxidation.

Constructing monodispersed metal sites in heterocatalysis is an efficient strategy to boost their catalytic performance. Herein, a new strategy using monodispersed metal sites to tailor Pt-based nanocatalysts is addressed by engineering unconventional p-d orbital hybridization. Thus, monodispersed Ga on Pt3 Mn nanocrystals (Ga-O-Pt3 Mn) with high-indexed facets was constructed for the first time to drive ethanol electrooxidation reaction (EOR). Strikingly, the Ga-O-Pt3 Mn nanocatalyst shows an enhanced EOR performance with achieving 8.41 times of specific activity than that of Pt/C. The electrochemical in situ Fourier transform infrared spectroscopy results and theoretical calculations disclose that the Ga-O-Pt3 Mn nanocatalyst featuring an unconventional p-d orbital hybridization not only promote the C-C bond-breaking and rapid oxidation of -OH of ethanol, but also inhibit the generation of poisonous CO intermediate species. This work discloses a promising strategy to construct a novel nanocatalysts tailored by monodispersed metal site as efficient fuel cell catalysts.

Synthesis of PtCuFe alloy nanoframes with high-index facets for efficient electro-oxidation of liquid fuels

By controlling the structure, surface and composition of Pt-based ternary alloy nanocrystals, the electro-catalytic performances of Pt-based catalysts can be improved effectively. In this paper, a one-pot method for synthesis of PtCuFe nanoframes (PtCuFe NFs) with tunable structure and defect density is reported. By controlling the heating mode and the type of ligand, then changing the nucleation/growth kinetics, two types of PtCuFe NFs were obtained. These types of catalysts exhibited excellent electro-catalytic performance for methanol electrooxidation (MOR) and formic acid electrooxidation (FAOR). Specifically, the dendritic nanoframes (d-NFs) showed high electro-catalytic activity for MOR and FAOR, which were 8.34 times and 3.68 times higher than commercial Pt/C, respectively. The stability was also greatly improved. The excellent electrocatalytic activity of PtCuFe NFs is attributed to the defect sites of high-index facets and open framework structures. This strategy provides a new idea for improving the electrocatalytic performance of Pt-based catalysts.

Boosting Electrocatalytic Hydrazine Oxidation Reaction on High-Index Faceted Au Concave Trioctahedral Nanocrystals

Boosting Electrocatalytic Hydrazine Oxidation Reaction on High-Index Faceted Au Concave Trioctahedral Nanocrystals

High-index facets and multidimensional hotspots in Au-decorated 24-faceted PbS for ultrasensitive and recyclable SERS substrates

24-faceted PbS–Au hybrids are prepared and used as ultrasensitive and recyclable SERS substrates due to their high-index facets, strong visible-near-infrared light absorption, multidimensional hotspots, abundant hotspots, and efficient charge transfer.

Synthesis of Carbon Black Loaded Pt Concave Nanocubes with High-Index Facets and Their Enhanced Electrocatalytic Properties Toward Glucose Oxidation

Synthesis of Carbon Black Loaded Pt Concave Nanocubes with High-Index Facets and Their Enhanced Electrocatalytic Properties Toward Glucose Oxidation

Helical PdPtAu nanowires bounded with high-index facets selectively switch the pathway of ethanol electrooxidation

This work reports the fabrication of helical PdPtAu NWs bounded with high-index facets for ethanol electrooxidation. The NWs can enhance the catalytic performance, and the selectivity of C1 products on Pd14Pt5Au2 NWs can be improved up to 23.2%.

Engineering PtCu nanoparticles for a highly efficient methanol electro-oxidation reaction.

Achieving a highly efficient and durable methanol electro-oxidation catalyst in acid media is critical for the practical utilization of direct methanol fuel cells (DMFCs) at the commercial scale. Herein, we report a facile and effective one-pot strategy for the synthesis of carbon-supported PtCu alloy nanoparticles (PtCu NPs) with a Pt-rich surface, small particle size and uniform dispersion. The as-prepared PtCu NPs with the optimal alloy composition (Pt2Cu) exhibit a significantly improved electrochemical methanol oxidation reaction performance in terms of a high activity, superior CO tolerance and remarkable durability, in contrast to those of commercial Pt/C catalysts in acid media. Particularly, the Pt2Cu/C catalyst exerts a 4.5 times enhancement in the mass activity and a larger If/Ib value compared to those of commercial Pt/C (Pt/Ccomm). The enhanced catalytic activities can be ascribed to the high utilization of Pt and the high index facets of the surface. Also, the addition of Cu downshifts the d-band center of Pt and improves the CO tolerance during the methanol oxidation reaction process. This work provides an efficient strategy for designing desired Pt-based alloys for various catalytic reactions.

In-situ Loaded Pt-Co High Index facets Catalysts: Preparation and Electrocatalytic Performance

In-situ Loaded Pt-Co High Index facets Catalysts: Preparation and Electrocatalytic Performance

Synthesis of gold nanocrystals with chiral morphology, chiral ligand and more exposed high-index facets as electrocatalyst for the oxidation of glucose enantiomers with high enantioselectivity and catalytic activity

We reported one way for synthesis of chiral gold nanocrystal.

Anomalous Kinetic Characteristics of Hydrogen Transport through Pd–Cu Membranes Modified by Pentatwinned Flower-Shaped Palladium Nanocrystallites with High-Index Facets

Anomalous Kinetic Characteristics of Hydrogen Transport through Pd–Cu Membranes Modified by Pentatwinned Flower-Shaped Palladium Nanocrystallites with High-Index Facets

Copper Nanoparticles with High Index Facets on Basal and Vicinal ZnO Surfaces

Copper Nanoparticles with High Index Facets on Basal and Vicinal ZnO Surfaces

Concave Double-Walled AgAuPd Nanocubes for Surface-Enhanced Raman Spectroscopy Detection and Catalysis Applications

Herein, we develop a series etching and atom codeposition process to fabricate concave double-shell AgAu (CD-AgAu) and CD-AgAu:Pd nanocubes. High surface area and edge activity from the CD nanostructure consisting of a single hole appear in the central area, and 12 concave structures exhibit superior surface-enhanced Raman scattering (SERS). As investigating the Pd dopants at the CD surface with SERS and electrochemistry, we demonstrate that the 2.8% Pd-doped CD-AgAu nanocubes perform impressive catalysis at ≤30 s of the hydrogenation reaction by lowering the activation energy. Furthermore, the CD-AgAu:4.6%Pd nanocubes act as a superior catalyst for glycerol electrooxidation and could retain their high-index facets after a long-term durability test. Our work will help to motivate future efforts for the deliberate incorporation of a low content of noble metals into CD nanostructures to develop chemical sensing devices in interfacial reactions and clean energy conversion technology.