Palladium nanoparticles supported by metal-organic frameworks derived FeNi3Cx nanorods as efficient oxygen reversible catalysts for rechargeable Zn-Air batteries

Metalloid tellurium-induced electron-deficient NiFe alloys awakening efficient oxygen electroreduction

Transition metal alloys catalysts have been extensively studied in oxygen reduction reactions (ORR); however, their suboptimal catalytic activity presents a significant challenge. Modifying the local electronic configuration of the catalytic active site by heteroatom doping is an effective strategy to enhance the electrocatalytic performance. Herein, an ORR Te/NiFe@NCNFs electrocatalyst, featuring with Te modified NiFe alloys nanoparticles and anchored on N-doped carbon nanofibers (NCNFs), was constructed via a surface-modified synthesis strategy. The introduction of Te leads to electron transfer on the surface of Te/NiFe@NCNFs, forming an electron-deficient NiFe site with high catalytic activity. Theoretical calculations confirm that Te regulates an electron redistribution and reduces the d-band centers of Fe and Ni, which help to facilitate the desorption of ORR intermediate oxides. As a result, Te/NiFe@NCNFs exhibit a half-wave potential of 0.86 V, superior to that of Pt/C (0.84 V) and most reported modified-NiFe-based catalysts. When assembled into a zinc-air battery, Te/NiFe@NCNFs deliver remarkable power density of 158.8 mW cm-2-2 and specific capacity of 778.1 mA h gZn-1. The present study presents new insights into the modulation of electronic structure in transition metal alloys, providing a feasible and innovative approach for the design of unrivaled ORR electrocatalysts.

Effect of Ni-Doping on the Optical, Structural, and Electrochemical Properties of Ag29 Nanoclusters

Atomically precise metal nanoclusters (NCs) can be compositionally controlled at the single-atom level, but understanding structure-property correlations is required for tailoring specific optical properties. Here, the impact of Ni atom doping on the optical, structural, and electrochemical properties of atomically precise 1,3-benzene dithiol (BDT) protected Ag29 NCs is studied. The Ni-doped Ag29 (NiAg28(BDT)12) NCs, are synthesized using a co-reduction method and characterized using electrospray ionization mass spectrometry (ESI MS), ion mobility spectrometry (IMS), and X-ray photoelectron spectroscopy (XPS). Only a single Ni atom doping can be achieved despite changing the precursor concentration. Ni doping in Ag29 NCs exhibits enhanced thermal stability, and electrocatalytic oxygen evolution reaction (OER) compared to the parent NCs. Density functional theory (DFT) calculations predict the geometry and optical properties of the parent and NiAg28(BDT)12 NCs. DFT is also used to study the systematic single-atom doping effect of metals such as Au, Cu, and Pt into Ag29 NCs and suggests that with Ni and Pt, the d atomic orbitals contribute to creating superatomic orbitals, which is not seen with other dopants or the parent cluster. The emission mechanism is dominated by a charge transfer from the ligands into the Ag core cluster regardless of the dopant.

A High-Energy-Density Magnesium-Air Battery with Nanostructured Polymeric Electrodes

The greenhouse emissions are biggest challenge of the present era. The renewable power sources are required to have characteristics of good charge capacity, energy density with proven charging discharging cycles for energy storage and applications. Mg-air batteries (MABs) are an alternative renewable power source due to their inexpensive cost. In particular, the previous reports presented the metal-air battery structure, with a specific energy overall output of 765 W h kg⁻¹. This paper is focused mainly on the MAB, which employed nanocomposite polymeric electrodes with a proven energy density of 545 W h kg⁻¹ and a charge capacity of 817 mA h g⁻¹ when electrolyzed at a cycling current density of 7 mA cm⁻².

Metal-organic frameworks as a good platform for the fabrication of multi-metal nanomaterials: design strategies, electrocatalytic applications and prospective

MOF-derived multi-metal nanomaterials are attracting numerous attentions in widespread applications such as catalysis, sensors, energy storage and conversion, and environmental remediation. Compared to the monometallic counterparts, the presence of foreign metal is expected to bring new physicochemical properties, thus exhibiting synergistic effect for enhanced performance. MOFs have been proved as a good platform for the fabrication of polymetallic nanomaterials with requisite features. Herein, various design strategies related to constructing multi-metallic nanomaterials from MOFs are summarized for the first time, involving metal nodal substitution, seed epitaxial growth, ion-exchange strategy, guest species encapsulation, solution impregnation and combination with extraneous substrate. Afterwards, the recent advances of multi-metallic nanomaterials for electrocatalytic applications, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), are systematically discussed. Finally, a personal outlook on the future trends and challenges are also presented with hope to enlighten deeper understanding and new thoughts for the development of multi-metal nanomaterials from MOFs.

Cooperative effect of bimetallic MOF-derived CoNi(OH)2@NiCo2S4nanocomposite electrocatalysts with boosted oxygen evolution activity

Highly efficient and inexpensive electrocatalysts for oxygen evolution reaction (OER) are extensively studied for water splitting. Herein, a unique bimetallic nanocomposite CoNi(OH)₂@NiCo₂S₄nanosheet arrays derived from metal-organic-frameworks (MOFs, CoNi-ZIF) is simply fabricated on Ni foam, endowing large specific surface area and outstanding electrical conductivity. Compared with their single-metallic counterparts, the bimetallic composite displays dramatically low overpotential and small Tafel slope as well as outstanding catalytic stability. The overpoptential at 20 mA cm^-2for CoNi(OH)₂@NiCo₂S₄is only 230 mV in comparison with Ni(OH)₂@Ni₃S₂(266 mV), Co(OH)₂@Co₃S₄(294 mV) and RuO₂(η = 302 mV). First-principle calculations based on density functional theory (DFT) are carried out and reveal that the introduction of Ni in Co(OH)₂helps lowered the energy difference of ΔG_OOH*-ΔG_O*, and thereby boosting the OER reactivity. This study provides an effective approach for the rational construction of low-cost metal hybrids.