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.

Ag-N-C single atom catalyst with resistance for Ag loss in acetylene hydrochlorination

Ag-N-C catalyst was synthesized by the calcination process with AgNO3as precursors, active carbon as support, and melamine as an N source. Series of characterizations showed that Ag was transferred into AgCl during the active phase by HCl, and pyridinic structure in the support was bonded with Ag components. Then, Ag-N-C single atom catalyst (SAC) was obtained by washing Ag-N-C with acid, aberration-correction high-angle-annular-dark-field scanning transmission electron microscopy showed that Ag presented in single atoms form, and Ag coordinated with the nitrogen atom in the support. Ag loss rate for Ag-N-C SAC was only 0.09% after running 10 h in acetylene hydrochlorination process, which was much smaller than Ag-N-C (57%), indicating that the presence of the Ag-N bond could be inhibiting Ag species loss.

Anchoring Copper Single Atoms on Porous Boron Nitride Nanofiber to Boost Selective Reduction of Nitroaromatics

Single-atom catalysts have received widespread attention for their fascinating performance in terms of metal atom efficiency as well as their special catalysis mechanisms compared to conventional catalysts. Here, we prepared a high-performance catalyst of single-Cu-atom-decorated boron nitride nanofibers (BNNF-Cu) via a facile calcination method. The as-prepared catalyst shows high catalytic activity and good stability for converting different nitro compounds into their corresponding amines both with and without photoexcitation. By combined studies of synchrotron radiation analysis, high-resolution high-angle annular dark-field transmission electron microscopy studies, and DFT calculations, dispersion and coordination of Cu atoms as well as their catalytic mechanisms are explored. The BNNF-Cu catalyst is found to have a record high turnover frequency compared to previously reported non-precious-metal-based catalysts. While the performance of the BNNF-Cu catalyst is only of the middle range level among the state-of-the-art precious-metal-based catalysts, due to the much lower cost of the BNNF-Cu catalyst, its cost efficiency is the highest among these catalysts. This work provides a choice of support material that can promote the development of single-atom catalysts.

Activated carbon supported Fe–Cu–NC as an efficient cathode catalyst for a microbial fuel cell

Herein, the output power density produced by Fe–Cu–NC-x as the cathode catalyst of a MFC was higher than that of the AC control.

PtM/Mx By (M=Ni, Co, Fe) Heterostructured Nanobundles as Advanced Electrocatalyst for Hydrogen Evolution Reaction

Optimizing the electronic and synergistic effect of hybrid electrocatalysts based on Pt and Pt-based nanocatalysts is of tremendous importance towards a superior hydrogen evolution performance under both acidic and alkaline conditions. However, developing an ideal Pt-based hydrogen evolution reaction (HER) electrocatalyst with moderated electronic structure as well as strong synergistic effect is still a challenge. Herein, we fabricated boron (B)-doped PtNi nanobundles by a two-step method using NaBH₄ as the boron source to obtain PtNi/Ni₄ B₃ heterostructures with well-defined nanointerfaces between PtNi and Ni₄ B₃ , achieving an enhanced catalytic HER performance. Especially, the PtNi/Ni₄ B₃ nanobundles (PtNi/Ni₄ B₃ NBs) can deliver a current density of 10 mA cm^-2 at the overpotential of 14.6 and 26.5 mV under alkaline and acidic media, respectively, as well as outstanding electrochemical stability over 40 h at the current density of 10 mA cm^-2 . Remarkably, this approach is also universal for the syntheses of PtCo/Co₃ B and PtFe/Fe₄₉ B with outstanding electrocatalytic HER performance.

Single-Atom Catalysts: A Sustainable Pathway for the Advanced Catalytic Applications

A heterogeneous catalyst is a backbone of modern sustainable green industries; and understanding the relationship between its structure and properties is the key for its advancement. Recently, many upscaling synthesis strategies for the development of a variety of respectable control atomically precise heterogeneous catalysts are reported and explored for various important applications in catalysis for energy and environmental remediation. Precise atomic-scale control of catalysts has allowed to significantly increase activity, selectivity, and in some cases stability. This approach has proved to be relevant in various energy and environmental related technologies such as fuel cell, chemical reactors for organic synthesis, and environmental remediation. Therefore, this review aims to critically analyze the recent progress on single-atom catalysts (SACs) application in oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and chemical and/or electrochemical organic transformations. Finally, opportunities that may open up in the future are summarized, along with suggesting new applications for possible exploitation of SACs.

Dual transition-metal atoms doping: an effective route to promote the ORR and OER activity on MoTe2

Compared to traditional single-atom doping method, the OER/ORR electrocatalytic activity of inert 2H-MoTe₂ can be efficiently triggered by properly dual TM atoms doping.

Theoretical Understandings of Graphene-based Metal Single-Atom Catalysts: Stability and Catalytic Performance

Research on heterogeneous single-atom catalysts (SACs) has become an emerging frontier in catalysis science because of their advantages in high utilization of noble metals, precisely identified active sites, high selectivity, and tunable activity. Graphene, as a one-atom-thick two-dimensional carbon material with unique structural and electronic properties, has been reported to be a superb support for SACs. Herein, we provide an overview of recent progress in investigations of graphene-based SACs. Among the large number of publications, we will selectively focus on the stability of metal single-atoms (SAs) anchored on different sites of graphene support and the catalytic performances of graphene-based SACs for different chemical reactions, including thermocatalysis and electrocatalysis. We will summarize the fundamental understandings on the electronic structures and their intrinsic connection with catalytic properties of graphene-based SACs, and also provide a brief perspective on the future design of efficient SACs with graphene and graphene-like materials.

Tailoring the Electronic Structure of Transition Metals by the V2C MXene Support: Excellent Oxygen Reduction Performance Triggered by Metal-Support Interactions

The enhancement of oxygen reduction reaction (ORR) activity can significantly boost the performance of fuel cells. MXene-supported transition metals with strong metal-support interactions (SMSI) are an effective strategy to increase the catalytic activity and durability while decreasing the usage of noble metals. Herein, a series of composites of transition-metal atoms (Ni, Pd, Pt, Cu, Ag, and Au) deposited on V₂C MXene are designed as potential catalysts for ORR using density functional theory. The calculation results demonstrate that all the transition metals prefer to form a monolayer on V₂C (TM_ML/V₂C) with high thermodynamic stability because of SMSI, in which the Pd, Pt, Ag, and Au monolayers exhibit high chemical stability during the ORR process. Pt_ML/V₂C exhibits the highest activity toward ORR with the overpotential down to 0.38 V and the largest energy barrier of 0.48 eV. The excellent catalytic performance originates from the modification of the electronic structure by the V₂C support because of SMSI. Our studies elucidate the SMSI between transition-metal atoms and V₂C MXene from the atomic level and thus rationally design the ORR catalyst at the cathode of fuel cells to enhance the activity while possessing high stability and less Pt usage.