Structural Transformation from Low-Coordinated Oxides to High-Coordinated Oxides during the Oxidation of Cu Nanoparticles

Abstract

Comprehensively understanding the oxidation mechanism of copper nanoparticles (NPs) is valuable to the corrosion protection of metals and controllable preparation of Cu oxide nanoparticles. In this work, we performed reactive molecular dynamics simulations to study the oxidation behaviors of Cu NPs. Results show that Cu NP oxidation is an expanding process from the surface oxidation nuclei to their surroundings, forming an oxide film and finally growing inward. In the process of oxide film formation, the oxide changes from a low-coordination structure to a high-coordination structure. Besides, the influences of oxygen content and temperature on the oxidation process have also been discussed. Excess oxygen contents at low temperature may have less effect on the oxidation, while the temperature rise can effectively promote oxidation and growth of high-coordinated oxides. This work provides a better understanding of the atomic-scale oxidation mechanism of Cu NPs, which is helpful to design and prepare the highly active, controllable, and stable Cu NPs.

Parallel-Self-Assembling Stack, Center-Capture Effect, and Reactivity-Enhancing Effect of N-Layer (N = 1, 2, 3) Cyclo[18]carbon

“…Recently, the RMD method , becomes a powerful computational tool for exploring the real-time reactive events between solid and gas interfaces, providing detailed information on both the reaction dynamics and the structural evolution. − In this work, the RMD simulations were applied to study the stacking behaviors of multilayer C 18 and the oxidation kinetics of N -layer ( N = 1, 2, 3) C 18 . The RMD method uses quantum mechanics structure and energy data to train empirical force fields and requires significantly fewer computational resources .…”

Copper Nanowires for Electrochemical CO2 Reduction Reaction

“…ReaxFF has been extensively used to structure or transition metals, including metal nanowires, 44,62 metal nanoparticles, 63 and Cu. 64 The initial structures of Cu NWs were generated by using the following procedure. One facet center cubic (FCC) unit cell, containing four atoms, was generated first and then replicated along three directions to generate the bulk structure.…”

“…In the hybrid GCMC/RMD simulations, the potential energy U of the Cu NWs was evaluated using ReaxFF as parametrized by Nielson et al to quantum mechanical data. ReaxFF has been extensively used to structure or transition metals, including metal nanowires, , metal nanoparticles, and Cu . The initial structures of Cu NWs were generated by using the following procedure.…”

Copper supported silica-based nanocatalysts for CuAAC and cross-coupling reactions

“…39 Furthermore, it's popularity in organic synthesis arises mostly from the following factors: (i) it may be capable of stabilizing various oxidation states, allowing for both one-and two-electron transfer (radical and ionic) pathways using radical or ionic Cu-based intermediates; (ii) it can easily bind to heteroatoms and enable the promotion of both interactions with unsaturated functional groups, providing for a variety of metal-reagent interactions; (iii) based on the Cu oxidation state and the nature of auxiliary ligands, it can also form coordination and organometallic complexes, as well as well-defined NPs, modifying their structures and compositions (or stabilizers for metal-based NPs); (iv) Cu-based NPs have proven to be effective catalysts for coupling processes (both homo-and hetero-couplings); and (v) moreover, these transformations are involved in the synthesis of a variety of organic compounds that are useful in a wide variety of sectors (medicinal chemistry, natural products, drugs, materials, etc.). 40 Cu-Based NP catalysts have recently been prepared using new methods that include the reduction of Cu (I) and Cu (II) salts, as well as organometallic complexes with SiO 2 supports. 41 Although the Cu (II) species are entirely reduced to zero-state Cu (0) NPs, electron-deficient Cu + sites generated by Fermi level electron loss or even residual cationic Cu species (with distinct oxidation states) may be crucial in permitting reactivity and selectivity trends.…”