The one-pot synthesis of CuNi nanoparticles with a Ni-rich surface for the electrocatalytic methanol oxidation reaction

Enhanced Hydroxyl Adsorption in Ultrathin NiO/Cr2 O3 In-Plane Heterostructures for Efficient Alkaline Methanol Oxidation Reaction

The exploration of advanced nickel-based electrocatalysts for alkaline methanol oxidation reaction (MOR) holds immense promise for value-added organic products coupled with hydrogen production, but still remain challenging. Herein, we construct ultrathin NiO/Cr2 O3 in-plane heterostructures to promote the alkaline MOR process. Experimental and theoretical studies reveal that NiO/Cr2 O3 in-plane heterostructures enable a favorable upshift of the d-band center and enhanced adsorption of hydroxyl species, leading to accelerated generation of active NiO(OH)ads species. Furthermore, ultrathin in-plane heterostructures endow the catalyst with good charge transfer ability and adsorption behavior of methanol molecules onto catalytic sites, contributing to the improvement of alkaline MOR kinetics. As a result, ultrathin NiO/Cr2 O3 in-plane heterostructures exhibit a remarkable MOR activity with a high current density of 221 mA cm-2 at 0.6 V vs Ag/AgCl, which is 7.1-fold larger than that of pure NiO nanosheets and comparable with other highly active catalysts reported so far. This work provides an effectual strategy to optimize the activity of nickel-based catalysts and highlights the dominate efficacy of ultrathin in-plane heterostructures in alkaline MOR.

Ni(II)-Incorporated Ethylene Glycol-Linked Tetraphenyl Porphyrin-Based Covalent Organic Polymer as a Catalyst for Methanol Electrooxidation

Methanol oxidation reaction (MOR) is a perfect alternative to the conventional oxygen evolution reaction (OER), generally utilized as the anode reaction for hydrogen generation via the electrochemical water splitting method. Moreover, MOR is also relevant to direct methanol fuel cells (DMFCs). These facts motivate the researchers to develop economical and efficient electrocatalysts for MOR. Herein, we have introduced an ethylene glycol-linked tetraphenyl porphyrin-based (EG-POR) covalent organic polymer (COP). The Ni(II)-incorporated EG-POR material Ni-EG-POR displayed excellent OER and MOR activities in an alkaline medium. The materials were thoroughly characterized using 13C solid-state NMR, Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area analyzer, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), and powder X-ray diffraction (PXRD) techniques. These organic-inorganic hybrid materials showed high chemical and thermal stability. Ni-EG-POR requires an overpotential of 400 mV (vs RHE) in OER and 190 mV (vs RHE) in MOR to achieve a current density of 10 mA cm-2. In addition, the catalyst also showed excellent chronoamperometric and chronopotentiometric stability, indicating that the catalyst can provide stable current over a longer period and its potential as a non-noble metal MOR catalyst.

Hierarchical N-doped carbon nanofiber-loaded NiCo alloy nanocrystals with enhanced methanol electrooxidation for alkaline direct methanol fuel cells

The high catalytic activity of non-precious metals in alkaline media opens a new direction for the development of alkaline direct methanol fuel cell (ADMFC) electrocatalysts. Herein, a highly dispersed N-doped carbon nanofibers (CNFs) -loaded NiCo non-precious metal alloy electrocatalyst based on metal-organic frameworks (MOFs) was prepared, which conferred excellent methanol oxidation activity and resistance to carbon monoxide (CO) poisoning through a surface electronic structure modulation strategy. The porous electrospun polyacrylonitrile (PAN) nanofibers and the P-electron conjugated structure of polyaniline chains provide fast charge transfer channels, enabling electrocatalysts with abundant active sites and efficient electron transfer. The optimized NiCo/N-CNFs@800 was tested as an anode catalyst for ADMFC single cell and exhibited a power density of 29.15 mW cm^-2. Due to the fast charge transfer and mass transfer brought by its one-dimensional porous structure and the synergistic effect between NiCo alloy, NiCo/N-CNFs@800 is expected to be an economical, efficient and CO-resistant methanol oxidation reaction (MOR) electrocatalyst.

Hydrogel Nanocomposite-Derived Nickel Nanoparticles/Porous Carbon Frameworks as Non-Precious and Effective Electrocatalysts for Methanol Oxidation

Innovative and facile methods for the preparation of metal nanoparticles (MNPs) with A highly uniform distribution and anchored on a unique substrate are receiving increasing interest for the development of efficient and low-cost catalysts in the field of alternative and sustainable energy technologies. In this study, we report a novel and facile metal-ions adsorption-pyrolysis method based on a hydrogel nanocomposite for the preparation of well-distributed nickel nanoparticles on 3D porous carbon frameworks (Ni@PCFs). The pyrolysis temperature effect on electrocatalytic activity toward methanol oxidation and catalyst stability was investigated. Physicochemical characterizations (SEM, TEM, and XRD) were used to determine the morphology and composition of the prepared electrocatalyst, which were then linked to their electrocatalytic activity. The experimental results indicate that the catalyst synthesized by pyrolysis at 800 °C (Ni@PCFs-8) exhibits the highest electrocatalytic activity for oxidation of methanol in alkaline media. Additionally, prepared Ni@PCFs-8 displays a remarkable increase in electrocatalytic activity after activation in 1 M KOH and excellent stability. The adsorption-pyrolysis pathway ensures that the Ni NPs are trapped in the PCFs, which can provide highly reactive surface sites. This work may provide a facile and effective strategy for preparing uniformly distributed metallic NPs on a 3D PCF substrate with high catalytic activity for energy applications.

Facile Preparation of Porous Carbon Flake-Supported Nickel Nanoplates as Effective Catalysts for Methanol Electrooxidation

Herein, we report a facile and efficient method for fabricating porous carbon flakes (PCFs)-supported nickel nanoplates (Ni NPs) as electrocatalysts for methanol oxidation in alkaline media. The catalyst was fabricated in one step using molten salt synthesis. Various techniques were used to characterize the morphology and composition of the Ni NPs@PCFs catalyst, and these revealed that the Ni NPs were dispersed finely across the PCFs with a highly crystalline structure. The Ni NPs@PCFs catalyst demonstrated high electrocatalytic activity for methanol oxidation (121 mA/cm2 vs. Ag/AgCl), and it had an onset potential of 0.35 V. It also exhibited high stability in an alkaline electrolyte for the duration of the experiment (up to 2000 s).

Dual-functioning porous catalysts: robust electro-oxidation of small organic molecules and water electrolysis using bimetallic Ni/Cu foams

The simultaneous co-deposition of Cu within the matrix of Ni foams (utilizing DHBT) increases their intrinsic catalytic activity towards water electrolysis, urea oxidation reaction (UOR), and glycerol oxidation reaction (GOR) in alkaline media.

Interstitial and substitutional light elements in transition metals for heterogeneous catalysis

The addition of foreign element dopants to monometallic nanoparticle catalysts is of great importance in industrial applications. Both substitutional and interstitial doping of pure metallic phases can give profound effects such as altering electronic and transport properties, lattice parameters, phase transitions, and consequently various physicochemical properties. For transition metal catalysts, this often leads to changes in catalytic activity and selectivity. This article provides an overview of the recent developments regarding the catalytic properties and characterisation of such systems. In particular, the structure-activity relationship for a number of important chemical reactions is summarised and the future prospects of this area are also explored.