Study of oxygen evolution reaction on amorphous Au13@Ni120P50 nanocluster

A comprehensive review of atomically precise metal nanoclusters with emergent photophysical properties towards diverse applications

Atomically precise metal nanoclusters (MNCs) composed of a few to hundreds of metal atoms represent an emerging class of nanomaterials with a precise composition. With the size approaching the Fermi wavelength of electrons, their energy levels are well-separated, leading to molecule-like properties, like discrete single electronic transitions, tunable photoluminescence (PL), inherent structural anisotropy, and distinct redox behavior. Extensive synthetic efforts and electronic structure revelation have expanded applicability of MNCs in catalysis, optoelectronics, and biology. This review highlights the intriguing photophysical and electrochemical behaviors of MNCs and their regulatory parameters and applications. Initially, we present a brief discussion on the evolution of MNCs from gas-phase naked metal clusters to monolayer ligand-protected MNCs along with representative studies on their electronic structure. Due to their quantized molecular orbitals, they often exhibit PL, which can be regulated based on their capping ligands, number of atoms, crystal packing, presence of heterometal, and surrounding environment. Apart from PL, the relaxation pathways of MNCs on an ultrafast time scale have been extensively studied, which significantly differ from that of plasmonic metal nanoparticles. Moreover, their interaction with high-intensity light results in unique non-linear optical properties. The synergy between MNCs in a hierarchical self-assembled structure has been exploited to enhance their PL by precisely tuning their non-covalent interactions. Moreover, several NC-based hybrids have been designed to exhibit efficient electron or energy transfer in the photoexcited state. In the next section, we briefly focus on the redox behavior of NCs and facile electron transfer to suitable substrates, which result in enzyme-like catalytic activity. Utilizing these photophysical and electrochemical behaviors, NCs are widely employed in catalysis, optical sensing, and light-harvesting applications, which are also discussed in this review. In the final section, conclusions and open questions for the NC research community are included. This review will provide a comprehensive view of the emerging physicochemical properties of MNCs, thereby enabling an understanding for their precise modulation in future.

Unraveling the Effects of Metal-Support Interaction on Nitrogen Reduction: A Theoretical Study in Au13/BiOCl

Understanding the mechanism of the nitrogen reduction reaction (NRR) is essential for designing highly efficient catalysts. In this study, we investigated the effects of the metal-support interaction (MSI) on NRR using density functional theory. The simulations revealed that the MSI is weak in the Au13/BiOCl system, with charge accumulation and depletion primarily occurring within the Au13 cluster. By replacement of one Au atom with either a Ag or Pt atom, the MSI becomes stronger compared to that in the Au13/BiOCl system. The is because doping breaks the symmetry of the Au13 cluster, leading to charge accumulation and depletion at the interface. Specifically, this enhanced MSI reduces the energy barriers of the rate-determining step from 1.07 eV in the Au13/BiOCl system to 0.91 eV in Au12Ag/BiOCl and 0.87 eV in Au12Pt/BiOCl, respectively. Our study uncovers the critical role of MSI in the activity of NRR, providing theoretical insights for the development of highly efficient NRR catalysts.

Controllable synthesis and electrocatalytic applications of atomically precise gold nanoclusters

Nanoclusters are composed of metal atoms and ligands with sizes up to 2-3 nm. Due to their stability and unique structure, gold nanoclusters with precise atomic numbers have been widely studied. Until now, atomically precise gold nanoclusters have been synthesised by various methods. Common ones include the Brust-Schiffrin method and the size-focusing method. With more detailed research on gold nanoclusters, more novel methods have been adopted to synthesise atomically precise gold nanoclusters, such as anti-galvanic reduction, ligand-exchange reactions from metal nanoclusters, the seed growth method, and so on. Besides, the nanoclusters also have many unique properties in electrochemical catalyses, such as the ORR, OER, etc., which are helpful for the development of the energy and environment. In this review, the synthesis methods and electrochemical applications of atomically accurate gold nanoclusters in recent years are introduced.

Metal Nanoclusters: New Paradigm in Catalysis for Water Splitting, Solar and Chemical Energy Conversion

A sustainable future demands innovative breakthroughs in science and technology today, especially in the energy sector. Earth-abundant resources can be explored and used to develop renewable and sustainable resources of energy to meet the ever-increasing global energy demand. Efficient solar-powered conversion systems exploiting inexpensive and robust catalytic materials for the photo- and photo-electro-catalytic water splitting, photovoltaic cells, fuel cells, and usage of waste products (such as CO₂ ) as chemical fuels are appealing solutions. Many electrocatalysts and nanomaterials have been extensively studied in this regard. Low overpotentials, catalytic stability, and accessibility remain major challenges. Metal nanoclusters (NCs, ≤3 nm) with dimensions between molecule and nanoparticles (NPs) are innovative materials in catalysis. They behave like a "superatom" with exciting size- and facet-dependent properties and dynamic intrinsic characteristics. Being an emerging field in recent scientific endeavors, metal NCs are believed to replace the natural photosystem II for the generation of green electrons in a viable way to facilitate the challenging catalytic processes in energy-conversion schemes. This Review aims to discuss metal NCs in terms of their unique physicochemical properties, possible synthetic approaches by wet chemistry, and various applications (mostly recent advances in the electrochemical and photo-electrochemical water splitting cycle and the oxygen reduction reaction in fuel cells). Moreover, the significant role that MNCs play in dye-sensitized solar cells and nanoarrays as a light-harvesting antenna, the electrochemical reduction of CO₂ into fuels, and concluding remarks about the present and future perspectives of MNCs in the frontiers of surface science are also critically reviewed.