Hydrogen peroxide (H 2 O 2), first synthesized in 1818 through the acidification of barium peroxide (BaO 2) with nitric acid, is a clear and colorless liquid which is entirely miscible with water and variety of organic solvents such as carboxylic acid and esters. Anthraquinone process (an old production process of H 2 O 2), a batch process carried out in large facilities is an energy demanding process that requires large facilities, and involves oxidation of anthraquinone molecules and sequential hydrogenation. Moreover, the direct synthesis method enables production in a continuous mode as well as it permits small scale, decentralized production. Many drawbacks associated with these processes such as, energetic inefficiency and inherent disadvantages have motivated researchers, industry and academia to find out alternative for synthesis of H 2 O 2. Electrochemical route based on catalyst selectively reduce oxygen to hydrogen peroxide. O 2 is cathodically reduced to produce H 2 O 2 via 2-electron pathway or 4-electron pathway to get H 2 O. Electrolysis of water has an important place in storage and electrochemical energy conversion process where problem is to choose a sufficiently stable and active electrode for anodic oxygen evolution reaction. Most commonly used catalysts on the cathode are carbon based materials such as carbon black, carbon nanotubes, graphite, carbon sponge, and carbon fiber. In perspective of expanding demand of production and usage of hydrogen peroxide we review the past literature to summarize different production processes of H 2 O 2. In this review, we mainly focus on electrochemical production of hydrogen peroxide along with other alternatives, such as anthraquinone method for industrial H 2 O 2 production and direct synthesis process. We also review the catalytic activity, selectivity and stability for enhanced yield of H 2 O 2. From revision of last two decade's literature including experimental and theoretical data; we argue that successful implementation of electrochemical H 2 O 2 production can be realized on the basis of stable, active and selective catalyst.

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Cadmium is a natural element found in the earth's crust. It is usually combined with other metals such as calcium or chromium. In single and associated form this metal is highly toxic. Our study is based on exposure of a fresh water zebra fish species named Danio rerio. This species is commonly used for metal exposure studies. Research was done by exposing the zebra fish to different concentration of cadmium (5 μg/L, 10 μg/L and 15 μg/L) for 8 days. Sampling was done on 0, 2, 4, 6, and 8 day respectively. Samples were frozen at -80 degrees. Physical parameters such as temperature, pH and salinity was checked and maintained regularly Later 1g of each sample were taken and digested through nitric acid digestion method. Concentration of cadmium accumulated in body of zebra fish was determined through the Atomic Absorption Spectrophotometer. Result showed the concentration of cadmium in body and number of deaths increased with increased in duration of exposure.