Interface-Mediated Synthesis of Transition-Metal (Mn, Co, and Ni) Hydroxide Nanoplates

We report a general and efficient strategy to produce monodisperse transition-metal (Mn, Co, and Ni) hydroxide nanoplates with tunable composition through the interface-mediated growth process. It is worth noting that, using common nitrates as the precursors, the as-obtained nanoplates were prepared under hydrothermal conditions. Moreover, the possible formation mechanism of the transition-metal hydroxide nanoplates has also been investigated. Subsequently, the resulting transition-metal hydroxides can be eventually transformed into transition-metal oxide nanoplates and lithium-ion intercalation materials through solid-state reactions, respectively. Furthermore, the electrochemical properties of the resulting nanomaterials have also been discussed in detail. This protocol may be easily extended to fabricate many other metal hydroxide and oxide nanomaterials

Single-Crystalline Octahedral Au–Ag Nanoframes

We report the formation of single-crystalline octahedral Au–Ag nanoframes by a modified galvanic replacement reaction. Upon sequential addition of AgNO₃, CuCl, and HAuCl₄ to octadecylamine solution, truncated polyhedral silver nanoparticles formed first and then changed into octahedral Au–Ag nanoframes, without requiring a conventional Ag removal step with additional oxidation etchant. The nanoframes have 12 sides, and all of the eight {111} faces are empty. The side grows along the [110] direction, and the diameter is less than 10 nm. The selective gold deposition on the high-energy (110) surface, the diffusion, and the selective redeposition of Au and Ag atoms are the key reasons for the formation of octahedral nanoframes

Syntheses of Water-Soluble Octahedral, Truncated Octahedral, and Cubic Pt–Ni Nanocrystals and Their Structure–Activity Study in Model Hydrogenation Reactions

We developed a facile strategy to synthesize a series of water-soluble Pt, Pt_<i>x</i>Ni_1‑<i>x</i> (0 < <i>x </i>< 1), and Ni nanocrystals. The octahedral, truncated octahedral, and cubic shapes were uniformly controlled by varying crystal growth inhibition agents such as benzoic acid, aniline, and carbon monoxide. The compositions of the Pt_<i>x</i>Ni_1‑<i>x</i> nanocrystals were effectively controlled by choice of ratios between the Pt and Ni precursors. In a preliminary study to probe their structure–activity dependence, we found that the shapes, compositions, and capping agents strongly influence the catalyst performances in three model heterogeneous hydrogenation reactions

Energy Upconversion in Lanthanide-Doped Core/Porous-Shell Nanoparticles

Here, we report upconversion nanoparticles with a core/porous-shell structure in which bulk emission and nanoemission are simultaneously observed. The activated porous shell can efficiently tune the bulk emission but has negligible influence on the nanoemission

Sophisticated Construction of Au Islands on Pt–Ni: An Ideal Trimetallic Nanoframe Catalyst

We have developed a priority-related chemical etching method to transfer the starting Pt–Ni polyhedron to a nanoframe. Utilizing the lower electronegativity of Ni in comparison to Au atoms, in conjunction with the galvanic replacement of catalytically active Au to Ni tops, a unique Au island on a Pt–Ni trimetallic nanoframe is achieved. The design strategy is based on the structural priority mechanism of multimetallic nanocrystals during the synthesis and thus can be generalized to other analogous metal–bimetallic nanocrystal combinations (such as Pd and Cu islands on Pt–Ni nanoframes), which is expected to pave the way for the future development of efficient catalysts

Defect-Dominated Shape Recovery of Nanocrystals: A New Strategy for Trimetallic Catalysts

Here we present a shape recovery phenomenon of Pt–Ni bimetallic nanocrystals that is unequivocally attributed to the defect effects. High-resolution electron microscopy revealed the overall process of conversion from concave octahedral Pt₃Ni to regular octahedral Pt₃Ni@Ni upon Ni deposition. Further experiments and theoretical investigations indicated that the intrinsic defect-dominated growth mechanism allows the site-selective nucleation of a third metal around the defects to achieve the sophisticated design of trimetallic Pt₃Ni@M core–shell structures (M = Au, Ag, Cu, Rh). Consideration of geometrical and electronic effects indicated that trimetallic atomic steps in Pt₃Ni@M could serve as reactive sites to significantly improve the catalytic performance, and this was corroborated by several model reactions. The synthesis strategy based on our work paves the way for the atomic-level design of trimetallic catalysts

Highly Active and Selective Catalysis of Bimetallic Rh₃Ni₁ Nanoparticles in the Hydrogenation of Nitroarenes

Because of the requirements of sustainable development as well as the desirability of using molecular hydrogen as a chemical reagent, it is of paramount importance and great challenge to develop highly active and selective catalysts for the hydrogenation of organic molecules, including substituted nitroarenes. We approach this question by probing unsupported bimetallic nanoparticles. A series of novel bimetallic Rh_<i>x</i>Ni_<i>y</i> (<i>x</i>, <i>y</i> = 1, 2, 3) nanoparticles were successfully prepared using our “noble metal-induced reduction” strategy. Unsupported Rh₃Ni₁ nanoparticles were subsequently identified to be a highly active and exceedingly selective catalyst for the hydrogenation of nitroarenes under ambient conditions, underscoring a remarkable synergistic effect of the two metals. Further experiments showed that the Rh₃Ni₁ catalyst could be a highly efficient, selective, and recyclable catalyst for a range of nitroarene substrates. This work showcased the value of bimetallic nanoparticles in catalysts development for sustainable chemistry

Room Temperature Activation of Oxygen by Monodispersed Metal Nanoparticles: Oxidative Dehydrogenative Coupling of Anilines for Azobenzene Syntheses

It is highly challenging but desirable to develop efficient catalysts for the activation of oxygen under mild conditions. Here, we report that various monodispersed metal nanoparticles (Ag, Pt, Co, Cu, Ni, Pd, and Au) efficiently activated molecular oxygen under mild conditions, illustrated by the aerobic oxidation of anilines to form either symmetric or asymmetric aromatic azo compounds. This discovery indicates that exploiting the catalytic power of nanoparticles could enable sustainable chemistry suitable for important oxidation reactions

Atomically Dispersed Au-Assisted C–C Coupling on Red Phosphorus for CO₂ Photoreduction to C₂H₆

Single-atom catalysts have exhibited great potential in the photocatalytic conversion of CO2 to C2 products, but generation of gaseous multi-carbon hydrocarbon products is still challenging. Previously, supports of a single atom consist of multiple elements, making C–C coupling difficult because the coordination environment of single-atom sites is diversified and difficult to control. Here, we steer C–C coupling by implanting an Au single atom on the red phosphorus (Au1/RP), support with uniform structure composed of a single element, lower electronegativity, and better ability to absorb CO2. The electron-rich phosphorus atoms near the Au single atoms can function as active sites for CO2 activation. The Au single atom can effectively reduce the energy barrier of C–C coupling, boosting the reaction kinetics of the formation of C2H6. Notably, the C2H6 selectivity and turnover frequency of Au1/RP reach 96% and 7.39 h–1 without a sacrificial agent, respectively, which almost represents the best photocatalyst for C2 chemical synthesis to date. This research will provide new ideas for the design of high-efficiency photocatalysts for CO2 conversion to C2 products

Modulating Alcohol Adsorption Modes for Boosting Electrooxidation-Assisted Hydrogen Production

Oxygen evolution reaction (OER) suffers from sluggish kinetics and results in the increasing cost of hydrogen production. The exploration of an appropriate anode organic reaction occurring at low potential represents a feasible strategy to accelerate the implementation of water splitting in practice. Herein, we develop a ligand-confining thermolysis strategy to fabricate a Ru single-atom catalyst (Ru-SA/NSC) on N,S-codoped carbon. The adsorption mode effects of substrate alcohols on the electrocatalytic oxidation of Ru-SA/NSC are unraveled through modulation of substituent groups. The horizontal adsorption through the O atom on Ru-SA/NSC significantly facilitates the benzyl alcohol oxidation, delivering ultralow potential of 0.97 V vs reversible hydrogen electrode (RHE) at 10 mA cm–2 with high yield (∼96%), selectivity (∼99%), and Faraday efficiency (∼100%) to produce aldehydes. The vertical adsorption through the N atom in pyridine methanol over Ru-SA/NSC has no response to the reaction. Furthermore, in the coupling device of alcohol oxidation and hydrogen evolution reaction, hydrogen production with a low potential of 1.21 V at 10 mA cm–2 is achieved, surpassing that of benchmark Pt/C||IrO2 (1.56 V) and the state-of-the-art reports. This study provides insights into the design of nanocatalysts toward the rational conversion of organic molecules to value-added chemicals and concurrently produces clean energy carriers