The discord between the insufficient abundance and the excellent electrocatalytic activity of Pt urgently requires its atomic-level engineering for minimal Pt dosage yet maximized electrocatalytic performance. Here we report the design of ultrasmall triphenylphosphine-stabilized Pt6 nanoclusters for electrocatalytic hydrogen oxidation reaction in alkaline solution. Benefiting from the self-optimized ligand effect and atomic-precision structure, the nanocluster electrocatalyst demonstrates a high mass activity, a high stability, and outperforms both Pt single atoms and Pt nanoparticle analogues, uncovering an unexpected size optimization principle for designing Pt electrocatalysts. Moreover, the nanocluster electrocatalyst delivers a high CO-tolerant ability that conventional Pt/C catalyst lacks. Theoretical calculations confirm that the enhanced electrocatalytic performance is attributable to the bifold effects of the triphenylphosphine ligand, which can not only tune the formation of atomically precise platinum nanoclusters, but also shift the d-band center of Pt atoms for favorable adsorption kinetics of *H, *OH, and CO. 

https://www.nature.com/articles/s41467-022-29276-7.pdf

Atomic-precision Pt6 nanoclusters for enhanced hydrogen electro-oxidation

Activation of aryl chlorides in cross-coupling reactions is a long-standing challenge in organic synthesis that is of great interest to industry. Ultrasmall (<3 nm), atomically precise nanoclusters (NCs) are considered one of the most promising catalysts due to their high surface area and unsaturated active sites. Herein, we introduce a copper nanocluster-based catalyst, [Cu61(StBu)26S6Cl6H14] (Cu61NC) that enables C-N bond-forming reactions of aryl chlorides under visible-light irradiation at room temperature. A range of N-heterocyclic nucleophiles and electronically and sterically diverse aryl/hetero chlorides react in this new Cu61NC-catalyzed process to afford the C-N coupling products in good yields. Mechanistic studies indicate that a single-electron-transfer (SET) process between the photoexcited Cu61NC complex and aryl halide enables the C-N-arylation reaction.

Visible-Light Copper Nanocluster Catalysis for the C-N Coupling of Aryl Chlorides at Room Temperature.

A large surface-to-volume ratio is one of the most intriguing characteristics of nanoclusters, which endows the nanoclusters with novel properties and applications. In this work, surface engineering with a functional DPPF ligand and Cd atom is employed on a Au38 nanocluster to obtain a Au–Cd alloy nanocluster, that is, Au27Cd1(SAdm)14(DPPF)Cl (Au27Cd1 in short, DPPF = 1,1′-bis(diphenylphosphino)ferrocene, HSAdm = 1-adamantanethiol). Various characterization techniques are used to characterize the precise formulation and atomic structure of the Au27Cd1 nanocluster. To demonstrate the influence of surface engineering on the properties of nanoclusters, the difference in optical, electrochemical and electrocatalytic activities in the oxygen reduction reaction (ORR) between Au38 and Au27Cd1, as well as the stability of Au27Cd1, is explored. The results indicate the importance of surface engineering, that is, the introduction of functional ligands and surface doping of Cd atoms contribute to the enhancement of catalytic activity. This work sheds light on the surface engineering of nanoclusters and provides a new perspective for the performance optimization of nanoclusters.

Construction of a new Au27Cd1(SAdm)14(DPPF)Cl nanocluster by surface engineering and insight into its structure–property correlation

Long-lasting yet visible-light-driven bacterial inhibition is highly desired for environmental protection and public health maintenance. However, conventional semiconductors such as titanium dioxide (TiO2) are impotent for such antibacterial application due to their low utilization rate for visible light. Herein we report the design of a long-lasting yet visible-light-driven antibacterial agent based on marrying luminescent Au nanoclusters (Au NCs for short) to TiO2 (TiO2-NH2@Au NCs). The as-obtained TiO2-NH2@Au NC antibacterial agent not only possesses superior utilization for visible light due to the participation of Au NCs as a good photosensitizer, but also has excellent separation efficacy of photogenerated carriers, thereby efficiently enhancing the generation of reactive oxygen species (ROS) for killing bacteria. Consequently, the TiO2-NH2@Au NCs display excellent antibacterial activity with good durability against both Gram-positive and Gram-negative bacteria such as Staphylococcus aureus (99.37%) and Escherichia coli (99.92%) under visible-light irradiation (λ ≥ 400 nm). This study is interesting because it provides a paradigm change in the design of long-lasting yet visible-light-driven NC-based antibacterial agents for diversified bactericidal applications.

Marrying luminescent Au nanoclusters to TiO2 for visible-light-driven antibacterial application

Solar‐energy‐powered photocatalytic fuel production and chemical synthesis are widely recognized as viable technological solutions for a sustainable energy future. However, the requirement of high‐performance photocatalysts is a major bottleneck. Halide perovskites, a category of diversified semiconductor materials with suitable energy‐band‐enabled high‐light‐utilization efficiencies, exceptionally long charge‐carrier‐diffusion‐length‐facilitated charge transport, and readily tailorable compositional, structural, and morphological properties, have emerged as a new class of photocatalysts for efficient hydrogen evolution, CO2 reduction, and various organic synthesis reactions. Despite the noticeable progress, the development of high‐performance halide perovskite photocatalysts (HPPs) is still hindered by several key challenges: the strong ionic nature and high hydrolysis tendency induce instability and an unsatisfactory activity due to the need for a coactive component to realize redox processes. Herein, the recently developed advanced strategies to enhance the stability and photocatalytic activity of HPPs are comprehensively reviewed. The widely applicable stability enhancement strategies are first articulated, and the activity improvement strategies for fuel production and chemical synthesis are then explored. Finally, the challenges and future perspectives associated with the application of HPPs in efficient production of fuels and value‐added chemicals are presented, indicating the irreplaceable role of the HPPs in the field of photocatalysis.

Stabilization and Performance Enhancement Strategies for Halide Perovskite Photocatalysts

Recently, the creation of new heterogeneous catalysts using the unique electronic/geometric structures of small metal nanoclusters (NCs) has received considerable attention. However, to achieve this, it is extremely important to establish methods to remove the ligands from ligand-protected metal NCs while preventing the aggregation of metal NCs. In this study, the ligand-desorption process during calcination was followed for metal-oxide-supported 2-phenylethanethiolate-protected gold (Au) 25-atom metal NCs using five experimental techniques. The results clearly demonstrate that the ligand-desorption process consists of ligand dissociation on the surface of the metal NCs, adsorption of the generated compounds on the support and desorption of the compounds from the support, and the temperatures at which these processes occurred were elucidated. Based on the obtained knowledge, we established a method to form a metal-oxide layer on the surface of Au NCs while preventing their aggregation, thereby succeeding in creating a water-splitting photocatalyst with high activity and stability.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ange.202104911

Creation of High-Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster

With global warming and the depletion of fossil resources, our fossil fuel-dependent society is expected to shift to one that instead uses hydrogen (H2) as a clean and renewable energy. To realize this, the photocatalytic water-splitting reaction, which produces H2 from water and solar energy through photocatalysis, has attracted much attention. However, for practical use, the functionality of water-splitting photocatalysts must be further improved to efficiently absorb visible (Vis) light, which accounts for the majority of sunlight. Considering the mechanism of water-splitting photocatalysis, researchers in the various fields must be employed in this type of study to achieve this. However, for researchers in fields other than catalytic chemistry, ceramic (semiconductor) materials chemistry, and electrochemistry to participate in this field, new reviews that summarize previous reports on water-splitting photocatalysis seem to be needed. Therefore, in this review, we summarize recent studies on the development and functionalization of Vis-light-driven water-splitting photocatalysts. Through this summary, we aim to share current technology and future challenges with readers in the various fields and help expedite the practical application of Vis-light-driven water-splitting photocatalysts.

/pdf/development-and-functionalization-of-visible-light-driven-23gal65n.pdf

Development and Functionalization of Visible-Light-Driven Water-Splitting Photocatalysts

Abstract Suppressing the amount of carbon dioxide in the atmosphere is an essential measure toward addressing global warming. Specifically, the photocatalytic CO2 reduction reaction (CRR) is an effective strategy because it affords the conversion of CO2 into useful carbon feedstocks by using sunlight and water. However, the practical application of photocatalyst‐promoting CRR (CRR photocatalysts) requires significant improvement of their conversion efficiency. Accordingly, extensive research is being conducted toward improving semiconductor photocatalysts, as well as cocatalysts that are loaded as active sites on the photocatalysts. In this review, we summarize recent research and development trends in the improvement of cocatalysts, which have a significant impact on the catalytic activity and selectivity of photocatalytic CRR. We expect that the advanced knowledge provided on the improvement of cocatalysts for CRR in this review will serve as a general guideline to accelerate the development of highly efficient CRR photocatalysts.

Promoting Photocatalytic Carbon Dioxide Reduction by Tuning the Properties of Cocatalysts

Single-atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H2) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g-C3N4; i.e., gCN), a promising visible-light-driven photocatalyst. A method is established to prepare SA-loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H2-evolution activity of the prepared metal SA-loaded gCN reveals that Pd, Pt, and Rh SA-loaded gCN exhibits relatively high H2-evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA-loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H2-evolution efficiency per SA than other metal SA-loaded gCN. Finally, the 8.6 times higher H2-evolution rate per active site of Pd SA is achieved than that of Pd-nanoparticles cocatalyst. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adfm.202303321

Yuki Akinaga

Papers

Creation of High-Performance Heterogeneous Photocatalysts by Controlling Ligand Desorption and Particle Size of Gold Nanocluster

Development and Functionalization of Visible-Light-Driven Water-Splitting Photocatalysts

Promoting Photocatalytic Carbon Dioxide Reduction by Tuning the Properties of Cocatalysts

Metal Single‐Atom Cocatalyst on Carbon Nitride for the Photocatalytic Hydrogen Evolution Reaction: Effects of Metal Species