The development of efficient, low-cost, and stable bifunctional catalysts is necessary for renewable energy storage and conversion, but it remains a challenge. Herein, we first report a novel strategy to develop WO 3 •nH 2 O (n = 0.33, 1.00, or 2.00) as a highly active and durable bifunctional catalyst for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in acidic media by controlling the degree of hydration. The content of solvated water molecules in WO 3 •nH 2 O can be precisely controlled by selectively using ethylenediaminetetraacetic acid or DL-malic acid for room-temperature precipitation synthesis. Structural flexibility associated with water solvation in WO 3 •nH 2 O leads to excellent bifunctional catalytic activity as well as durability in acidic media. The bifunctional catalytic mechanism of WO 3 •nH 2 O is mainly attributed to spontaneous partial dehydration during electrolysis, resulting in simultaneous formation of active phases for HER and ORR, respectively.
Modulating the metal-support interaction (MSI) have been of rational approach to enhance the kinetics of the supported Pt-based nanocatalysts for oxygen reduction reaction (ORR). However, sluggish activity and poor durability...
The polishing is one of the important methods in manufacturing of silicon wafer and in thinning of completed device wafer. Generally, getting a flat surface such as a mirror is the purpose of the process. The wafer surface roughness is affected by many variables such as the characteristics of the carrier head unit, operation, speed, the pad and slurry temperature. Optimum process conditions for experimental temperature, down-force, slurry ratio are investigated, time is used as a fixed factor. This study will report the evaluation on surface of wafer by dependent of varying platen, chuck rpm, temperature variation, and oscillation which affect it has on the surface roughness. In this experiment, it is determined the optimum condition for polishing silicon wafers. By using optimum condition, it helps to achieve an ultra precision mirror like surface.
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