BCC-Cu nanoparticles: from a transient to a stable allotrope by tuning size and reaction conditions

Abstract

Metallic copper generally adopts an FCC structure. In this work, we detect highly unusual BCC-structured Cu nanoparticles as a transient intermediate during the H2 reduction of a CuI precursor, [Cu4OtBu4],...

Combining Atomic Layer Deposition with Surface Organometallic Chemistry to Enhance Atomic-Scale Interactions and Improve the Activity and Selectivity of Cu–Zn/SiO2 Catalysts for the Hydrogenation of CO2 to Methanol

“…Component 1 corresponds to Cu 1+ species with a pre-edge feature, a white line region (intensity and profile), and edge energy reminiscent of Cu 2 O (yet a minor amount of Cu 0 may be present, as mentioned above). Both component 2 and component 3 are consistent with Cu 0 species, as evidenced by the characteristic edge profile and the white line doublet at around 9000 eV. , Components 2 and 3 differ slightly in the intensity of the white line region, with component 3 having a doublet feature of lower intensity and a more smoothly rising edge profile, indicative of either an increased structural disorder that might arise from thermal effects or alloying; the latter explanation is consistent with the MCR-ALS analysis of the Zn K-edge data discussed below.…”

“…The reduction of Cu is further supported by EXAFS data (its fitting is discussed in Supporting Information ), although EXAFS analysis cannot exclude the presence of a minor amount of Cu 0 in passivated Cu–Zn(5)/SiO 2 prior to in situ H 2 treatment. 50 , 51 Summarizing, in situ Cu K-edge XAS data are consistent with the formation of the Cu 0 state in the activated Cu–Zn(5)/SiO 2 .…”

“…Analysis of the Cu K-edge XANES data before and after H 2 pretreatment reveals that Cu is transformed from Cu 1+ (edge energy of 8980.3 eV) to a reduced state (8979.0 eV, Figure S53). The reduction of Cu is further supported by EXAFS data (its fitting is discussed in Supporting Information), although EXAFS analysis cannot exclude the presence of a minor amount of Cu 0 in passivated Cu–Zn(5)/SiO 2 prior to in situ H 2 treatment. , Summarizing, in situ Cu K-edge XAS data are consistent with the formation of the Cu 0 state in the activated Cu–Zn(5)/SiO 2 .…”

Tailoring Cu–SiO2 Interaction through Nanocatalyst Architecture to Assemble Surface Sites for Furfural Aqueous-Phase Hydrogenation to Cycloketones

“…Attempts to estimate the proportion of reduced copper in Cu/SiO 2 and NPCu/SiO 2 samples by linear combination fit between CuO and Cu 2 O did not lead to satisfactory results. The other three samples, namely NPCu@SiO 2 , NPCu@SiO 2 (calcined), and SiO 2 @Cu, show spectra characteristic of Cu 0 with an fcc structure, 56 being those of NPCu@SiO 2 and SiO 2 @Cu flattened with respect to NPCu@SiO 2 , suggesting the influence of size effects on XANES oscillations (smaller copper domains). Notwithstanding, the NPCu@SiO 2 spectrum shows a higher whiteline intensity and a perceivable feature within the edge (∼8985 eV), which can be ascribed to a small fraction of Cu 2+ , most likely arising from copper oxidation.…”

Scalable synthesis of Cu(-Ag) oxide clusters via spark ablation for the highly selective electrochemical conversion of CO2 to acetaldehyde

“…Finally, we exclude the presence of BCC crystal structures reported previously, by means of simulation (Figure S28). 53 For reasons of clarity, we show only a subset of the simulated XANES spectra of the particles. For the complete set, see Figure S29.…”