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The dynamic process of crevice corrosion during anodic dissolution of a crevice electrode in a 5.0 mmol dm-3 NaCl solution has been studied by digital holographic reconstruction. Digital holographic reconstruction has been proved to be an effective and in situ technique to detect the changes in the solution concentration because useful and direct information can be obtained from the three-dimensional images. It provides a valuable method for a better understanding of the mechanism of crevice corrosion by studying the dynamic processes of changes in the solution concentration at the interface of crevice corrosion.

L-Glutamine was used to form monolayers for the inhibition of the corrosion of iron in 0.50 mol dm-3 H2SO4. The protection ability of the films was examined by electrochemical impedance spectroscopy. The mechanism of adsorption is discussed using quantum chemical calculations and molecular simulations. Scanning electron microscopy was applied to confirm the formation of L-glutamine monolayers and the inhibitive effect. The results indicate that the molecules of L-glutamine are able to form films on the surface of iron and longer immersion time of the iron electrode in the solution results in a stronger inhibition ability of the films. The films are formed spontaneously by the adsorption of L-glutamine with a specific affinity of its head-group to the iron surface, hence, the densely and ordered monolayers can be considered as self-assembled.

Symmetry‐breaking synthesis of colloidal nanocrystals with desired structures and properties has aroused widespread interest in various fields, but the lack of robust synthetic protocols and the complex growth kinetics limit their practical applications. Herein, a general strategy is developed to synthesize the Au–Cu Janus nanocrystals (JNCs) through the site‐selective growth of Cu nanodomains on Au nanocrystals, which is directed by the substantial lattice mismatch between them, with the assistance of judicious manipulation of the growth kinetics. This strategy can work on Au nanocrystals with different architectures for the achievement of diverse asymmetric Au–Cu hybrid nanostructures. Of particular note, the obtained Au nanobipyramids (Au NBPs)‐based JNCs facilitate the conversion of CO2 to C2 hydrocarbon production during electrocatalysis, with the Faradaic efficiency and maximum partial current density being 4.1‐fold and 6.4‐fold higher than those of their monometallic Cu counterparts, respectively. The excellent electrocatalytic performances benefit from the special design of the Au–Cu Janus architectures and their tandem catalysis mechanism as well as the high‐index facets on Au nanocrystals. This research provides a new approach to synthesize various hybrid Janus nanostructures, facilitating the study of structure‐function relationship in the catalytic process and the rational design of efficient heterogeneous electrocatalysts. [ABSTRACT FROM AUTHOR]

Hybrid photocatalysts containing plasmonic metal and semiconductor building blocks can alleviate charge carrier recombination and broaden the range of light absorption of the semiconductor. In this work, plasmonic Au nanocrystals of different sizes and shapes (spheres and rods) are attached on graphitic carbon nitride (g-C3N4) nanosheets through electrostatic attraction. The effects of the morphology and loading amount of the Au nanocrystals are carefully studied for understanding and optimizing the hybrid photocatalysts. The optimized 18 nm-sized Au nanospheres/g-C3N4 photocatalyst exhibits a superior activity for H2 evolution at a rate of 540 μmol g−1 h−1 under visible light (λ ＞ 420 nm), exceeding those produced over larger-sized Au nanospheres/g-C3N4, Au nanorods/g-C3N4 and photodeposited Au nanoparticles/g-C3N4 photocatalysts. The excellent activity for H2 evolution is attributed to the electron sink and plasmonic effects of the Au nanocrystals in different spectral regions, as evidenced by photocurrent measurements. The introduced plasmonic Au nanocrystals not only enhance the photocatalytic activity, but they also endow the hybrid photocatalysts with an extended light absorption range. Our results and understanding will be useful for the design of efficient plasmonic photocatalysts for solar to fuel energy conversion as well as for other plasmon-driven chemical reactions. [ABSTRACT FROM AUTHOR]

Absorption-dominant small Au nanorodswith diameters of less than10 nm are prepared using a facile seed-mediated growth method. Thediameters of the small gold nanorods range from 6 to 9 nm, and theirlengths vary from 16 to 45 nm. Their aspect ratios can be tailoredfrom 2.7 to 4.7. As a result, the longitudinal plasmon resonance wavelengthsare readily tunable from ∼720 nm to ∼830 nm by changingthe seed-to-Au(III) molar ratio in the growth solution. The fractionsof the scattering in the total extinction of the small Au nanorodsare found to be in the range of 0.005 to 0.025 with finite-differencetime-domain simulations, confirming that the extinction values ofthese small Au nanorods are dominantly contributed to by the lightabsorption. Moreover, the small Au nanorod sample is coated with adense silica layer for photothermal therapy with three cell lines.It shows improved photothermal therapy performance compared to a largeAu nanorod sample for the same cellular Au contents. Our study suggeststhat small Au nanorods are promising light absorbers and photothermaltherapy agents. [ABSTRACT FROM AUTHOR]

Developing photocatalysts that can efficiently produce hydrogen from water under solar irradiation is highly desired for sustainable and clean hydrogen energy. Herein, it is demonstrated that (TiO2(B) nanosheet)/(metallic phase MoS2) hybrid nanostructures have high activity for photocatalytic hydrogen evolution from water. The TiO2(B) nanosheets are prepared by solvothermal reaction with TiCl3 as a precursor in the presence of ethylene glycol. Due to the short transportation distance of charge carriers, more negative conduction band edge, and the existence of oxygen vacancy, the photocatalytic activity of the pure TiO2(B) nanosheets is one order of the magnitude larger than that of the commercial P25. After loading metallic phase MoS2, the photocatalytic activity of TiO2(B) is further improved by ≈13 times to 1444 μmol g−1 h−1 because of the superior activity of metallic phase MoS2 for hydrogen evolution. The findings provide a cost‐effective and highly active photocatalyst for hydrogen production from water and are very helpful for the development of sustainable and clean hydrogen energy. [ABSTRACT FROM AUTHOR]

Precise manipulation of the reactive site spatial distribution in plasmonic metal/semiconductor photocatalysts is crucial to their photocatalytic performance, but the construction of Janus nanostructures through symmetry-breaking synthesis remains a significant challenge. Here we demonstrate a synthetic strategy for the selective growth of a CeO 2 semi-shell on Au nanospheres (NSs) to fabricate Janus Au NS/CeO 2 nanostructures with the assistance of a SiO 2 hard template and autoredox reaction between Ag + ions and a ceria precursor. The obtained Janus nanostructures possess a spatially separated architecture and exhibit excellent photocatalytic performance toward N 2 photofixation under visible-light illumination. In this scenario, N 2 molecules are reduced by hot electrons on the CeO 2 semi-shell, while hole scavengers are consumed by hot holes on the exposed Au NS surface, greatly promoting the charge carrier separation. Moreover, the exposed Au NS surface in the Janus structures offers an additional opportunity for the fabrication of ternary Janus noble metal/Au NS/CeO 2 nanostructures. This work highlights the genuine superiority of the spatially separated nanoarchitectures in the photocatalytic reaction, offering instructive guidance for the design and construction of novel plasmonic photocatalysts., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Plasmonic hot electrons have shown great potential in photocatalysis, but little is known about the hot hole-driven chemical reactions due to the lack of desired plasmonic metal/p-type semiconductor architectures. Herein, we describe a general and robust strategy for the site-selective growth of a p-type semiconductor, Cu 2 O on Au nanocrystals (NCs), to produce diverse spatially separated Au/Cu 2 O heterostructures. The preferential growth of Cu 2 O on the tips/ends/edges of Au NCs is directed by the sparse coverage of the surfactant molecules at the high-curvature sites of Au NCs. The obtained dumbbell-shaped nanostructures serve as the ideal platforms for probing the hot-hole-mediated CO 2 reduction reaction. Benefiting from the hot-hole injection, a new reaction pathway is unlocked, and the C 2 product activity and selectivity are significantly improved. This study demonstrates the genuine superiority of the dumbbell-shaped nanostructures in photocatalysis, offering a new unique avenue to explore the underlying mechanism of hot-hole-mediated chemical reactions.

Photocatalytic conversion of carbon dioxide (CO 2 ) to liquid product acetaldehyde (CH 3 CHO) remains a great challenge due to the involvement of a complex 10-electron reduction process and a sluggish C-C coupling reaction. Herein, we report the synthesis of Janus silver/ternary silver halide (Ag/AgClBr) nanostructures through precisely manipulating the growth kinetics and its function as a plasmonic photocatalyst to boost the conversion of CO 2 to CH 3 CHO. The obtained Janus nanostructures featuring both spatially separated architecture and broad light-harvesting capability facilitate the photocatalytic reduction of CO 2 under solar illumination. The photocatalytic CO 2 reduction with the characteristics of high activity and good selectivity can generate a 10-electron reduction product CH 3 CHO with a generation rate of 209.3 ± 9.5 μmol h -1 g -1 and a selectivity of 96.9%, which are rarely achieved in previously reported photocatalytic CO 2 reduction systems. The excellent photocatalytic performance can be ascribed to the plasmonic effect of Ag nanocrystals and the favorable active sites on the catalyst surface. This research demonstrates for the first time the utilization of the Janus Ag/AgClBr nanostructures to generate the value-added C 2 liquid product through photocatalytic CO 2 reduction, paving the way for the design and construction of novel plasmonic photocatalysts.

Hybrid photocatalysts containing plasmonic metal and semiconductor building blocks can alleviate charge carrier recombination and broaden the range of light absorption of the semiconductor. In this work, plasmonic Au nanocrystals of different sizes and shapes (spheres and rods) are attached on graphitic carbon nitride (g-C3N4) nanosheets through electrostatic attraction. The effects of the morphology and loading amount of the Au nanocrystals are carefully studied for understanding and optimizing the hybrid photocatalysts. The optimized 18 nm-sized Au nanospheres/g-C3N4 photocatalyst exhibits a superior activity for H2 evolution at a rate of 540 μmol g-1 h-1 under visible light (λ > 420 nm), exceeding those produced over larger-sized Au nanospheres/g-C3N4, Au nanorods/g-C3N4 and photodeposited Au nanoparticles/g-C3N4 photocatalysts. The excellent activity for H2 evolution is attributed to the electron sink and plasmonic effects of the Au nanocrystals in different spectral regions, as evidenced by photocurrent measurements. The introduced plasmonic Au nanocrystals not only enhance the photocatalytic activity, but they also endow the hybrid photocatalysts with an extended light absorption range. Our results and understanding will be useful for the design of efficient plasmonic photocatalysts for solar to fuel energy conversion as well as for other plasmon-driven chemical reactions.