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School of Energy and Chemical EngineeringThe interest in hydrogen energy is rapidly increasing worldwide for developing renewable and clean energy. Among various hydrogen production methods, green hydrogen source produced by solar energy is a promising way with zero emission. Photoelectrochemical (PEC) water splitting system is widely considered as one of most promising systems to generate green hydrogen since PEC system can produce green hydrogen by using water and solar energy, and when hydrogen energy is used, it can form the most ideal energy cycle. The categories of PEC system can be broadly divided into two parts: photoanode and photocathode. We have focused photoanode part by using ??-Fe2O3 called as hematite. Hematite is one of the cheapest materials used as a photoanode and has outstanding potential to theoretically achieve an efficiency of 15% solar-to-hydrogen (STH) conversion efficiency. In hematite-based photoanode, a variety of categories can be formed such as substrate, underlayer, overlayer, doping, oxygen evolution co-catalyst (OEC), and surface treatment. Herein, in the OEC part, we present an approach to minimize the light shielding effect by OEC in hematite surface. By successfully selectively adsorbing the developed Ti doped FeOOH (Ti-FeOOH) co-catalyst into the inner surface (inside pores) of hematite, Ti-FeOOH/Ti doped porous hematite (Ti-PH) shows a photocurrent density of 4.06 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) with good stability for 36 hours. In addition, we have focused on enhancing the performance of hematite itself and have been studying the synergy effect that can achieve structural evolution and doping through surface treatment at the same time as well as problems that may occur in the fabrication process. We cover two case of Si doping and Ge doping, respectively, and show the effects of dopants on hematite. Both cases utilize an overlayers of SiOx and GeO2, and Sn diffusion into hematite from the fluorine-doped tin oxide (FTO) coated glass can be suppressed when the overlayers are used. In the case of Si doping, we demonstrate the deep mechanism by which Si can be easily doped with Si and Ti interaction with efficient structural evolution. NiFeOx coated Si and Ti co-doped hematite shows 4.3 mA cm-2 at 1.23 V vs. RHE without any demanding fabrication process. In the case of Ge doping, we present that when Sn doping from FTO is suppressed, Ge is less affected by Sn and can make more efficient Ge doping effect. After decorating NiFeOx co-catalyst, NiFeOx/Ge doped porous hematite (Ge-PH) shows a photocurrent density of 4.6 mA cm-2 at 1.23 V vs. RHE and our tandem device with a perovskite solar cell (PSC) achieves 4.8% STH efficiency. Our works suggests a straightforward way to develop efficiently doped hematite, that can be easily expanded to other doping systems for green hydrogen production.ope

Carbon-Supported Fe2O3 and TiO2 Photoanodes for Enhanced Photoelectrochemical Cell Performance

Department of Chemical EngineeringSince the worldwide demands for energy is increasing, the consideration of environmental issues has been sharply required. Developing clean, low-cost and renewable fuel sources is a key challenge facing mankind in order to meet the energy and environment demands. Electrolysis of water is one of the methods of hydrogen generation. However, it is an energy intensive process. To produce clean energy, such as hydrogen, photoelectrochemical (PEC) cell is widely considered as one of most promising methods to split water when driven by abundant solar energy. We have focused photoanode materials, hematite and titanium dioxide, which is one of PEC components. In the hematite case, we have shown that by coupling graphene inverse opal structure with hematite, the problem of low diffusion length and low absorption in hematite was efficiently addressed, and thereby the water splitting photocurrent density generated by hematite could be greatly enhanced. This study can be readily extended to other metal oxide materials and systems, which provide strong potential for our strategy in energy conversion system. In the case of titanium dioxide, we made heterojunction with cadmium selenide (CdSe) for visible range absorption. However, CdSe quantum dot is often unstable in water under irradiation of light due to their relatively slower interfacial hole transfer kinetics as compared to their electron injection rates. To overcome this problem, we have successfully fabricated a novel graphene quantum dot supported CdSe-sensitized photoanode for visible-working PEC system. By modifying photoanode with graphene quantumdot, photocurrent density was retained almost unchanged for 300 minutes irradiation and the photocurrent density increased by 1.2 times relative to that without graphene quantum dot. Our work suggests a straightforward way to develop efficient and durable quantum-dot-sensitized photoanodes for PEC hydrogen generation.ope

A humeral hemiarthroplasty with biologic resurfacing of the glenoid using an allo-Achilles tendon: two case reports

A hemiarthroplasty with biologic resurfacing of the glenoid is one procedure that can be performed in young patients where total shoulder arthroplasty may be difficult. The authors introduced two cases in which this procedure was performed. This approach is one treatment option for young glenoid humeral arthritis patients that addresses some of the shortcomings of an isolated hemiarthroplasty

Current Status of Trace Metal Pollution in Soils Affected by Industrial Activities

There is a growing public concern over the potential accumulation of heavy metals in soil, owing to rapid industrial development. In an effort to describe the status of the pollutions of soil by industrial activities, relevant data sets reported by many studies were surveyed and reviewed. The results of our analysis indicate that soils were polluted most significantly by metals such as lead, zinc, copper, and cadmium. If the dominant species are evaluated by the highest mean concentration observed for different industry types, the results were grouped into Pb, Zn, Ni, Cu, Fe, and As in smelting and metal production industries, Mn and Cd in the textile industry, and Cr in the leather industry. In most cases, metal levels in the studied areas were found to exceed the common regulation guideline levels enforced by many countries. The geoaccumulation index (Igeo), calculated to estimate the enrichment of metal concentrations in soil, showed that the level of metal pollution in most surveyed areas is significant, especially for Pb and Cd. It is thus important to keep systematic and continuous monitoring of heavy metals and their derivatives to manage and suppress such pollution