Tailoring the deposition of MoSe2 on TiO2 nanorods arrays via radiofrequency magnetron sputtering for enhanced photoelectrochemical water splitting

MoSe2/1 D TiO2 nanorods (NRs) heterojunction assembly was systematically fabricated, and its photoelectrocatalytic properties were investigated. The fabrication process involves the growth of 1D TiO2 NRs arrays on FTO substrates using hydrothermal synthesis followed by the deposition of MoSe2 nanosheets on the TiO2 NRs using radiofrequency magnetron sputtering (RF magnetron sputtering). The photoelectrochemical properties of the heterojunction were explored and optimized as a function of the thickness of the MoSe2 layer, which was controlled by the sputtering time. The MoSe2 grows perpendicularly on TiO2 NRs in a 2D layered structure, maximizing the exposed active edges, an essential aspect that permits maximum exploitation of deposited MoSe2. Compared to pure TiO2 NRs, the heterojunction nanostructured assembly displayed excellent spectral and photoelectrochemical properties, including more surface oxygen vacancies, enhanced visible-light absorption, higher photocurrent response, and decreased charge transfer resistance. In particular, the sample synthesized by sputtering of MoSe2 for 90 s, i.e., MoSe2@TiO2-90 s, depicted the highest current density (1.86 mA cm−2 at 0.5 V vs. Ag/AgCl) compared to other samples. The excellent photoelectrochemical activity of the heterojunction stemmed from the synergy between tailored loading of MoSe2 nanosheets and the 1D structure of TiO2 NRs, which afford a high surface/volume ratio, effective charge separation, fast electron transfer, and easy accessibility to the MoSe2 active edges. These factors boost the catalytic activity.This work was made possible by NPRP Grant no. NPRP 12S-0304-190218 from the Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. Open Access funding provided by the Qatar National Library.Scopu

Lower Colorado River Basin

Presented at River basin management to meet competing needs: proceedings from the USCID conference on shared rivers held on October 21-31, 1998 in Park City, Utah.Specific entities in Arizona, California, and Nevada, (herein referenced as the Lower Basin states), are entitled to use in the aggregate either more than, an amount equal to, or less than 7.5 million acre-feet (maf) of Colorado River water in a year depending upon a determination to be made by the Secretary of the Interior (Secretary). In 1996, net water diversions from the Colorado River in the Lower Basin states exceeded 7.5 maf for the first time after accounting for unmeasured return flows. Net diversions in the Lower Basin states also exceeded 7.5 maf in 1997. It is projected that net diversions will exceed 7.5 maf in 1998 as well. Although entities in each state are entitled to use a certain yearly apportionment in the aggregate, entities in a Lower Basin state can utilize the unused apportionments of another Lower Basin state, subject to the approval of the Secretary. Also, entities in each state can use surplus Colorado River water when water in excess of 7.5 maf is available, as determined by the Secretary. No doubt, improved management of Colorado River water in each of the Lower Basin states is a challenge and a key element in meeting future demands to ensure economic stability and sustained development. Capital expenditures are necessary to improve water use efficiency by agricultural and urban users, and to facilitate cooperative programs in which agricultural users reduce their use of water to permit urban users to maintain their level of use. For several decades, California has been exploring and implementing a spectrum of programs aimed at improving the management of its water supplies and reducing its dependence on Colorado River water. A brief description of several of these programs is presented. To date, major progress has occurred. Continued cooperative efforts among water agencies are needed for the timely implementation of additional identified water resources management programs to ensure the availability of reliable water supplies of high quality for future generations

Short-term water transfer programs

Presented at Competing interests in water resources - searching for consensus: proceedings from the USCID water management conference held on December 5-7, 1996 in Las Vegas, Nevada.The Metropolitan Water District of Southern California (Metropolitan) and the Palo Verde Irrigation District implemented a two-year test land fallowing program (Program) from August 1, 1992 through July 31, 1994. Under the Program, 20,215 acres of agricultural farmland in the Palo Verde Valley were fallowed. The saved water, approximately 186,000 acre-feet, was stored in Lake Mead by the United States for use by Metropolitan prior to the year 2000. Metropolitan compensated participating farmers $620 per fallowed acre per year which equated to$135 per acre-foot of water saved. Four surveys were conducted in the Palo Verde Valley during and after the Program to evaluate the economic impacts of the Program on the participating farmers and the community as a whole. Results showed that the Program was well received by the farmers and various community representatives, and that the Program contributed to a slight reduction in the average regional employment, approximately 1.3 percent. Participating farmers reportedly spent 93 percent of Program payments in excess off allowing and maintenance costs on farm-related investments, purchases, and debt repayment. Although this Program had relatively small economic impacts, nevertheless it is a difficult task to quantify the positive and negative impacts of water transfer programs. Further details relating to the Program, third party impacts, and the regional economic impacts of the Program are presented

Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements

This paper discusses the state of the art in the application of self-healing silicone-based materials for outdoor high-voltage insulation. Both the dynamic behavior of the dimethyl side groups of silicone rubber and the diffusion of a bulk siloxane to maintain low surface energy are respectively reported as intrinsic mechanisms responsible for the self-healing of silicone rubber. Localization, temporality, mobility, and the type of synthesis are the aspects defining the efficiency of the self-healing ability of silicone rubber. In addition, the deterioration of the self-healing ability with filler loaded into silicone rubber insulation housing composites is discussed. Taking the self-healing property into consideration among the other properties of silicone rubber insulators, such as tracking and erosion resistance, can be a useful design practice at the material development stage. Hydrophobicity retention, recovery, and transfer measurements are discussed as useful indicators of the self-healing ability of silicone rubber. Nevertheless, there remains a need to standardize them as design tests at the material development stage. The paper is intended to shed the light on the hydrophobicity recovery, a key material design parameter in the development of silicone rubber outdoor insulating composites, similar to the tracking and erosion resistance

Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements

This paper discusses the state of the art in the application of self-healing silicone-based materials for outdoor high-voltage insulation. Both the dynamic behavior of the dimethyl side groups of silicone rubber and the diffusion of a bulk siloxane to maintain low surface energy are respectively reported as intrinsic mechanisms responsible for the self-healing of silicone rubber. Localization, temporality, mobility, and the type of synthesis are the aspects defining the efficiency of the self-healing ability of silicone rubber. In addition, the deterioration of the self-healing ability with filler loaded into silicone rubber insulation housing composites is discussed. Taking the self-healing property into consideration among the other properties of silicone rubber insulators, such as tracking and erosion resistance, can be a useful design practice at the material development stage. Hydrophobicity retention, recovery, and transfer measurements are discussed as useful indicators of the self-healing ability of silicone rubber. Nevertheless, there remains a need to standardize them as design tests at the material development stage. The paper is intended to shed the light on the hydrophobicity recovery, a key material design parameter in the development of silicone rubber outdoor insulating composites, similar to the tracking and erosion resistance.Acknowledgments: F. Kamand, B. Mehmood, A. El-Hag, M. Hassan, L. Al-Sulaiti, and A. Abdala acknowledge that this work was made possible by NPRP grant 12S-0227-190168 from Qatar National Research Fund (a member of Qatar Foundation) and the Qatar University International collaboration grant #: IRCC-2020-010. The statements made herein are solely the responsibility of the authors: F. Kamand, B. Mehmood, A. El-Hag, M. Hassan, L. Al-Sulaiti, and A. Abdala.Scopu