Oxygen vacancies (OVs) are a mixed blessing for the photoelectrochemical (PEC) water oxidation performance of monoclinic tungsten trioxide (m‐WO3) photoanodes. Although it is widely accepted that a moderate concentration of OVs is beneficial for the PEC performance of the m‐WO3 photoanodes, this argument assumes a uniform distribution of OVs throughout the m‐WO3 crystal. In this case, only the overall concentration of OVs needs to be considered. However, the spatial non‐uniformity of OV defects in m‐WO3 photoanodes has not been thoroughly examined. In this study, by employing a m‐WO3 nanorod array as a model photoanode, the aim is to show that a higher OV concentration near the surface of m‐WO3 compared to that in the bulk is advantageous for the PEC performances of this material. In addition, a laser‐assisted defect control (LADC) process is employed to manipulate the spatial distribution of OVs in the m‐WO3 photoanodes to achieve enhanced PEC performances. Moreover, a one‐step laser deposition process is introduced to obtain an ultrathin FeNi oxygen evolution catalyst overlayer on the defect‐controlled m‐WO3 photoanodes, further improving PEC performance, photostability, and Faradaic efficiency.

Spatial Control of Oxygen Vacancy Concentration in Monoclinic WO3 Photoanodes for Enhanced Solar Water Splitting

Designing materials with electron/mass transfer effectively improves catalytic activity by synergistic effects between different species. Herein, we report a high-temperature pyrolysis strategy to induce charge transfer of Cu3P loaded TiO2 3D hollow mesoporous carbon nanospheres (Cu3P/TiO2@NC). Density functional theory (DFT) calculations disclose that synergistic between Cu3P and TiO2 can optimize the adsorption of oxygen intermediates and endow fast reaction kinetics. Cu3P/TiO2@NC with hollow mesoporous structure can establish a favorable three-phase interface and shorten the electronic/mass transport path to accelerate reaction kinetics. Consequently, Cu3P/TiO2@NC indicated robust electrocatalytic activity in alkaline medium compared to single-component catalysts and benchmark Pt/C. Cu3P/TiO2@NC exhibits a greater power density of 182.9 mW cm−2 and excellent cyclability over 220 h than Pt/C + RuO2 in Zn-air battery. The flexible properties endow Cu3P/TiO2@NC with promising application prospects in wearable electronic devices. This work may provide an avenue to construct hollow-porous-structured catalysts with synergistic effects for renewable energy devices. 

Synergistic effect and nanostructure engineering of three-dimensionally hollow mesoporous spherical Cu3P/TiO2 in aqueous/flexible Zn–air batteries

Activation of chloride by oxygen vacancies-enriched TiO2 photoanode for efficient photoelectrochemical treatment of persistent organic pollutants and simultaneous H2 generation.

Role of Lithium Doping on α-Fe2O3 Photoanode for Enhanced Photoelectrochemical Water Oxidation

The work function engineering in metal-oxide nanostructures by judicious doping of impurities is not straightforward as it introduces multiple defects in the system. In this regard, understanding the nitrogen (N) doping-induced modulation of Fermi levels in TiO2 nanotubes (TNTs) is challenging for visible-range photocatalytic applications. Here, 50 keV N ions are implanted in TNTs with a fluence range of 1014–1016 ions/cm2. X-ray diffraction and micro-Raman analyses demonstrate the formation of anatase-TiO2 in pristine TNTs, while the crystalline quality is significantly affected by increasing ion fluence. The evolution of Ti3+ is also established by X-ray photoelectron spectroscopy, whereas ultraviolet photoelectron spectroscopy reveals the reduction in work function due to the formation of oxygen vacancies, in good agreement with X-ray absorption spectroscopy and photoluminescence results. The electron paramagnetic resonance study further identifies the evolution of Ti3+/N-substitutional defect centers. Finally, an enhancement in visible-light-assisted methylene blue and Rhodamine B dye degradation is recorded up to a fluence of 1 × 1015 ions/cm2, and it is correlated with the N-ion implantation-induced formation of electrochemically active states near the conduction band minimum and the valence band maximum. The decrease in degradation efficiency beyond a critical fluence of 1015 ions/cm2 is discussed on the ground of ion-beam-mediated amorphization and the subsequent increase in electron–hole recombination in the defect states. 

Modulation of the Work Function of TiO2 Nanotubes by Nitrogen Doping: Implications for the Photocatalytic Degradation of Dyes

Oxygen vacancies have been treated as an important material engineering tool to enhance catalytic performance; for instance, oxygen vacancies suppress charge recombination at the Schottky interface, and thus, the photocurrent can be improved. In this regard, the gradient distribution of oxygen vacancies in n‐type metal oxides produces the ideal band structure for minimizing e−/h+ recombination by efficient hole extraction; however, its achievement remains a daunting challenge. Here, a photoelectrochemical (PEC)‐driven “self‐purification” process is suggested, which can effectively generate a gradient distribution of oxygen vacancies in the thickness range of ≈9.5 nm. As a result, a charge transport efficiency of >95% can be achieved by efficient hole migration from the photoanode to the electrolyte. This unique protocol is expected to provide an advanced metal oxide photocatalyst and photoelectrochemical electrode that exhibit superior photocatalytic performance with enhanced charge separation.

Continuous Oxygen Vacancy Gradient in TiO2 Photoelectrodes by a Photoelectrochemical‐Driven “Self‐Purification” Process

The water–gas shift reaction (WGSR) is important in industries because it can reduce the CO content of syngas to produce purified H2, which can be used as fuel or to make ammonia (NH3). Supported noble metal catalysts have been widely studied for the WGSR because they exhibit high reactivity. However, the role of a metal–support interface in the WGSR has not yet been revealed and remains elusive. Density functional theory (DFT) calculations were performed for a model system of Co3O4-supported Pd (Pd/Co3O4) catalysts. The presence of the interface was found to promote the H2O dissociation step, which is crucial for improving WGSR activity. Thus, the WGSR activity was predicted to be enhanced by an increased number of interfaces, which could be achieved by controlling the size of the supported Pd nanoparticles (NPs). Furthermore, electronic metal–support interactions (MSIs) were found to be a source of the promoted H2O dissociation at the interface. The DFT-predicted promotion of H2O dissociation was further experimentally validated using Pd/Co3O4 catalysts that were size-controlled with calcination temperatures, and the total length of the interface was shown to have a direct correlation with the WGSR rate. Theoretical insights into the role of the interface and the enhancement of WGSR activity due to increased interface sites, which can be achieved by size control, are believed to be useful in the design of efficient supported metal catalysts for the WGSR. 

Role of an Interface for Hydrogen Production Reaction over Size-Controlled Supported Metal Catalysts

/pdf/development-of-tigernuts-galsu-for-lactating-women-s-water-18904t5gn9.pdf

Development of Tigernuts Galsu for Lactating Women's Water Supply and Skin Care

The electrochemical ozone evolution reaction (OZER) via a six-electron water-oxidation reaction can benefit the water–energy nexus. Herein, we report a straightforward heterojunction strategy to tune the OZER activity and selectivity...

Tuning Electrochemical Water Oxidation towards Ozone Evolution by Heterojunction Anode Architectures

Purpose: This study analyzed the quality properties of cookies made with sea tangle powder in order to improve bowel movements in pregnant women. Methods: To identify the optimal sensory mixing ratio using response surface analysis of sea tangle cookies with sea tangle powder and sugar as independent variables and following a central composite design, which is required for optimizing manufacturing conditions. Results: Based on the results of modeling experimental results and verification of significance, a linear model was selected for color (brightness, redness, yellowness) and moisture content, a 2FI model was selected for hardness and a quadratic model was selected for spreadability. Sea tangle powder was the most significant variable affecting brightness, redness, and yellowness among the mechanical characteristics of cookies. These characteristics were inversely correlated with the amount of sea tangle powder added (p<0.01). Hardness was positively correlated with the amount of sugar (p<0.05), and spreadability was also positively correlated with the amount of sea tangle powder (p<0.05). The test results for the sensory characteristics of cookies made with sea tangle powder showed that the amount of sea tangle powder increased color, smell, flavor, texture, and overall preferences with positive correlations. However, these properties began to decrease at a certain point, where additional sea tangle powder made cookies worse in terms of smell (p<0.01), flavor (p<0.05), and overall quality (p<0.05). Conclusion: Taken together, the optimal mixing ratio for cookies made with sea tangle powder was 5.80 g of sea tangle and 50.71 g of sugar. This study suggests that cookies made with sea tangle powder are effective in relieving constipation in pregnant women.

Seo Yeong Choung

Papers

Continuous Oxygen Vacancy Gradient in TiO2 Photoelectrodes by a Photoelectrochemical‐Driven “Self‐Purification” Process

Role of an Interface for Hydrogen Production Reaction over Size-Controlled Supported Metal Catalysts

Development of Tigernuts Galsu for Lactating Women's Water Supply and Skin Care

Tuning Electrochemical Water Oxidation towards Ozone Evolution by Heterojunction Anode Architectures

Optimization of Sea Tangle Cookies for Improving Constipation Activity of Pregnant Women