Semiconductor photocatalysts are hardly employed for overall water splitting beyond 700 nm, which is due to both thermodynamic aspects and activation barriers. Metallic materials as photocatalysts are known to overcome this limitation through interband transitions for creating electron-hole pairs; however, the application of metallic photocatalysts for overall water splitting has never been fulfilled. Black tungsten nitride is now employed as a metallic photocatalyst for overall water splitting at wavelengths of up to 765 nm. Experimental and theoretical results together confirm that metallic properties play a substantial role in exhibiting photocatalytic activity under red-light irradiation for tungsten nitride. This work represents the first red-light responsive photocatalyst for overall water splitting, and may open a promising venue in searching of metallic materials as efficient photocatalysts for solar energy utilization.
Background In China, tobacco smoking accounts for approximately 800 000 deaths annually and evidence suggests that tobacco use is rising. To improve tobacco control initiatives directed at youth, we conducted a population-based survey of children ages 11-20 years, both in and out of school. While there have been previous school-based studies on smoking prevalence and smoking-related knowledge, attitudes, and behaviours among adolescents in China, including the Global Youth Tobacco Survey, this survey also describes smoking behaviour among nonstudent youth. This population is important as approximately 40% of Chinese youths aged 15-19 years have already discontinued their studies.
Organometallic halide perovskite solar cells (PSCs) are rapidly evolving as the promising photovoltaic technologies with high record efficiency over 24%. The inorganic p‐type semiconductor NiOx is extensively used as important hole transport layers for the realization of stable and hysteresis‐free solar cells due to their good electronic properties, facile fabrication, and excellent chemical endurance. However, the critical issues of NiOx films including poor intrinsic conductivity and mismatched band alignment limit further improvement of the device performance. Herein, it is demonstrated that a versatile alkaline earth metal (Mg, Ca, Sr, and Ba) doping strategy can effectively engineer the electronic properties of NiOx contacts in inverted planar PSCs. Alkaline earth metal doping can deepen valence band maximum and enhance the hole conductivity of NiOx films, which better aligns the energy band in solar cells. The champion device based on Sr‐doped NiOx films attains a power conversion efficiency of 19.49% with a high open‐circuit voltage (VOC) of 1.14 V for NiOx‐based CH3NH3PbI3 devices. The resulted device shows negligible hysteresis and high stability as well. This finding provides a systematic doping strategy to further improve the performance of inverted planar PSCs.
The synthesis of methanethiol from H 2 S-rich syngas was investigated over sulfided Mo-based catalysts supported on SiO 2 . At CO/H 2 /H 2 S = 1/1/2, 0.2 MPa, 3,000 h -1 , and 300°C, mainly CH 3 SH, COS, and CO 2 were formed, along with small amounts of hydrocarbons and thioethers over potassium-promoted Mo-based catalysts. Studies of the reaction pathway show that COS is a primary product, which is hydrogenated to CH 3 SH and H 2 O. Most of CO 2 originates from water-gas shift reaction. The hydrocarbons and thioethers originate from the hydrogenation of CH 3 SH.
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