Significant Aggregation-Enhanced Carrier Separation in Nanoscopic Catalysts Heterojunction Stacks

Nanoscopic heterojunction stacks are prevalent in nature as well as in artificial material systems, such as the nanoscopically blended components in soil or artificial catalytic layers on device surfaces. Despite the enormous attention placed on studying individual heterojunctions, the advantageous catalytic performance of heterojunction aggregates has not been recognized. In this study, we employ the ordered N-doped TiO2 nanosheets and Au nanoparticle heterojunction multilayers obtained by a layer-by-layer technique to investigate the functional merits stemmed from heterojunction aggregates. The study demonstrates that nanoscopic heterojunction stacks promote the internal electric field that stemmed from charge separation and boost carrier separations. The aggregate-enhanced carrier separation can be harnessed in chemical conversions. The enhancement effect is influenced by both the dimensions of the entire aggregates as well as the dimensions of the nanoscopic building units. We expect the study to promote the understanding of heterojunction catalysts and corresponding matter conversion from the individual particulate level to the nanoscopic aggregate level and facilitate better harnessing of the photovoltaic effects or catalytic power in nanoscopic heterojunction aggregates

Sub‑3 nm CoO Nanoparticles with Oxygen Vacancy-Dependent Catalytic Activity for the Oxygen Reduction Reaction

Developing transition metal-based electrocatalysts toward the oxygen reduction reaction (ORR) with high activity has attracted much attention for high-powered electrochemical energy conversion devices. Earth-abundant and low-cost cobalt oxide has attracted ever-growing interest; however, insufficient active sites and poor electrical conductivity hamper the improvement of catalytic activity for the ORR. Herein, the high-dispersed ultra-small CoO nanoparticles on three-dimensional porous carbon are synthesized by a facile wet chemistry and low-temperature calcination strategy. The characterization with multiple techniques shows that the oxygen vacancy defects are in situ formed on sub-3 nm CoO, and oxygen vacancy concentrations can be adjusted to investigate the related ORR performance. The computational and experimental results demonstrate that moderate oxygen vacancy concentration in CoO improves electrical conductivity, reduces the energy barrier in the rate-limiting step, and optimizes the adsorption of *O and *OH intermediates, thus achieving a high half-wave potential of 0.80 V and a limiting current density of 5.26 mA cm–2. This work points out an avenue to the future design of high-efficiency metal oxides for diverse renewable energy applications

Additional file 1 of Sexual violence against women remains problematic and highly prevalent around the world

Additional file 1: Supplementary Table 1. Quality assessment of cross-sectional studies*

Attapulgite Doped with Fe and Cu Nanooxides as Peroxidase Nanozymes for Antibacterial Coatings

The search for low-cost, highly efficient, and stable nanozymes mimicking peroxidase (POD) enzymes remains a great challenge in the development of valuable antibacterial applications. Herein, a natural attapulgite (ATP)-supported Fe and Cu oxide with mixed valences (Fe-Cu/ATP) is reported as an efficient nanozyme by a feasible impregnation method. The obtained Fe-Cu/ATP nanozyme with a large specific area and high dispersity can effectively catalyze the hydrogen peroxide (H2O2) decomposition, exhibiting enhanced POD-like activity compared with Fe/ATP, Cu/ATP, and pristine ATP. In addition, the Fe-Cu/ATP showed high stability and reusability. Through further combination with the density functional theory calculation, the electron density of the ATP surface is increased by simultaneously introducing Fe and Cu dopants. Thus, Fe-Cu/ATP possesses excellent antibacterial properties including a short-time effect depending on the POD-like activity with H2O2 and a long-term effect generated by the metal without H2O2. Finally, a coating desktop and an antibacterial fabric were delicately designed and fabricated by loading Fe-Cu/ATP onto polyethylene and a fabric surface, showing the enormous potential of Fe-Cu/ATP as building and medical functional coatings. This study provides a rational way to design natural mineral nanozymes for promising antibacterial applications