(Zn,H)-codoped copper oxide nanoparticles via pulsed laser ablation on Cu-Zn alloy in water

Defect-Rich CuZn Nanoparticles for Model Catalysis Produced by Femtosecond Laser Ablation

Femtosecond laser ablation of Cu0.70Zn0.30 targets in ethanol led to the formation of periodic surface nanostructures and crystalline CuZn alloy nanoparticles with defects, low-coordinated surface sites, and, controlled by the applied laser fluence, different sizes and elemental composition. The Cu/Zn ratio of the nanoparticles was determined by energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and selected area electron diffraction. The CuZn nanoparticles were about 2-3 nm in size, and Cu-rich, varying between 70 and 95%. Increasing the laser fluence from 1.6 to 3.2 J cm-2 yielded larger particles, more stacking fault defects, and repeated nanotwinning, as evident from high-resolution transmission electron microscopy, aided by (inverse) fast Fourier transform analysis. This is due to the higher plasma temperature, leading to increased random collisions/diffusion of primary nanoparticles and their incomplete ordering due to immediate solidification typical of ultrashort pulses. The femtosecond laser-synthesized often nanotwinned CuZn nanoparticles were supported on highly oriented pyrolytic graphite and applied for ethylene hydrogenation, demonstrating their promising potential as model catalysts. Nanoparticles produced at 3.2 J cm-2 exhibited lower catalytic activity than those made at 2.7 J cm-2. Presumably, agglomeration/aggregation of especially 2-3 nm sized nanoparticles, as observed by postreaction analysis, resulted in a decrease in the surface area to volume ratio and thus in the number of low-coordinated active sites.

Copper-Nanocoated Ultra-Small Cells in Grain Boundaries Inside an Extinct Vent Chimney

Chemosynthetic organisms flourish around deep-sea hydrothermal vents where energy-rich fluids are emitted from metal sulfide chimneys. However, microbial life hosted in mineral assemblages in extinct chimneys lacking fluid venting remains largely unknown. The interior of extinct chimneys remains anoxic where the percolation of oxygenated seawater is limited within tightly packed metal sulfide grains. Given the scarcity of photosynthetic organics in deep seawater, anaerobic microbes might inhabit the grain boundaries energetically depending on substrates derived from rock-water interactions. In this study, we reported ultra-small cells directly visualized in grain boundaries of CuFeS₂ inside an extinct metal sulfide chimney from the southern Mariana Trough. Nanoscale solid analyses reveal that ultra-small cells are coated with Cu₂O nanocrystals in grain boundaries enriched with C, N, and P. In situ spectroscopic and spectrometric characterizations demonstrate the distribution of organics with amide groups and a large molecular organic compound in the grain boundaries. We inferred that the ultra-small cells are anaerobes because of the fast dissolution of Cu₂O nanocrystals in oxygenated solution. This Cu₂O property also excludes the possibility of microbial contamination from ambient seawater during sampling. It is shown by 16S rRNA gene sequence analysis that the chimney interior is dominated by Pacearchaeota known to have anaerobic metabolisms and ultra-small cells. Our results support the potential existence of photosynthesis-independent microbial ecosystems in grain boundaries in submarine metal sulfides deposits on the early Earth.

Synthesis of Zn:Cu2O thin films using a single step electrodeposition for photovoltaic applications

Zinc-doped cuprous oxide (Zn:Cu2O) thin films have been prepared via single step electrodeposition from an aqueous solution containing sodium perchlorate. The Zn/Cu molar ratio in the Zn:Cu2O films can be tuned between 0.006 and 0.236 by adjusting the magnitude of the applied potential and the sodium perchlorate concentration. Electrical characterization reveals that zinc dopants increase the Fermi level in Zn:Cu2O films, enabling a 3-fold improvement in the power conversion efficiency of a fully electrodeposited Cu2O homojunction photovoltaic device.

The sonochemical approach improves the CuO–ZnO/TiO2 catalyst for WGS reaction

The CuO–ZnO/TiO₂ catalyst prepared by the ultrasound assisted method demonstrates superior activity in water gas shift reaction in comparison with the catalysts synthesized by incipient wetness impregnation. The sonochemical preparation offers at least two advantages: (1) generation of mesopores on the catalyst surface and (2) doping of Zn into the CuO phase.