Advanced Development Strategy of Nano Catalyst and DFT Calculations for Direct Synthesis of Hydrogen Peroxide

Abstract

Hydrogen peroxide is a simple oxidizing agent. Its environmental benignness and effectiveness have led to a continuous increase in its use and production. Anthraquinone autoxidation (the AO process) is generally used to manufacture hydrogen peroxide (H2O2); however, this complex multi‐stage process releases large amounts of organic solvent into the environment and requires significant energy to operate. As a green and energy‐efficient production method, the direct synthesis of hydrogen peroxide (DSHP) from molecular hydrogen and oxygen can overcome the disadvantages of the AO process. However, DSHP has remained challenging until recently as severe mass‐transfer limitations and unavoidable side reactions result in insufficient selectivity for H2O2. However, beyond the conventional development methods for catalysts, recent advances in chemical and engineering fields can appreciably assist in the discovery of a “dream catalyst” for DSHP; high‐end computational methods and the facile surface‐controllable syntheses of nanocatalysts. This review addresses how a combination of density functional theory (DFT) calculations and nanocatalyst synthesis technologies lead to the development of high‐performance catalysts for DSHP, and provides guidelines on efficient methodologies for the development of catalysts through the use of cutting edge technologies.

Greatly Facilitated Two-Electron Electroreduction of Oxygen into Hydrogen Peroxide over TiO2 by Mn Doping

“…Hydrogen peroxide (H 2 O 2 ), a high-value oxidant, is used vastly in industry, including wastewater treatment, paper manufacturing, and chemical synthesis . Its industrial production still requires a centralized and costly anthraquinone process operating in large plants, which also involves multistep redox reactions with unwanted organic wastes. − H 2 O 2 can also be directly produced from H 2 and O 2 ; however, the H 2 and O 2 mixture involves explosion risks. , Two-electron (2e – ) electroreduction of O 2 into H 2 O 2 in an aqueous environment provides a safe, sustainable, and energy-saving approach for on-demand production, but the electrochemical reduction of O 2 preferentially proceeds via the four-proton and four-electron reduction routes to generate water, posing a formidable challenge for catalysts to promote the 2e – pathway. − …”

“…1−3 H 2 O 2 can also be directly produced from H 2 and O 2 ; however, the H 2 and O 2 mixture involves explosion risks. 4,5 Two-electron (2e − ) electroreduction of O 2 into H 2 O 2 in an aqueous environment provides a safe, sustainable, and energy-saving approach for ondemand production, but the electrochemical reduction of O 2 preferentially proceeds via the four-proton and four-electron reduction routes to generate water, posing a formidable challenge for catalysts to promote the 2e − pathway. 6−9 Although noble metal-containing materials remain the most active 2e − oxygen reduction reaction (2e − ORR) electrocatalysts, their practical-scale use is unfortunately impeded by low abundance and high costs.…”

Three-in-One Strategy to Improve Both Catalytic Activity and Selectivity: Nonconcentric Pd–Au Nanoparticles

“…The nonconcentric Pd–Au structures have three exposed regions of Pd domains, Au domains, and Pd–Au interfaces (hence, the 3-in-1 strategy), which implies that three intrinsic properties may synergistically be activated from a single NP structure. The Au domains can offer inactive surface sites resulting from the fully occupied d-bands and thus prevent O 2 dissociation and byproduct formation. − The Pd domains can facilitate the H 2 conversion process. , Last, the Pd–Au interfaces can serve as interesting active sites because the Pd domain offers facile H 2 dissociation and the Au domain suppresses O 2 dissociation; therefore, H 2 O 2 can be produced at the Pd/Au interfaces. Based on these results, nonconcentric Pd–Au NPs can be considered promising candidates for direct H 2 O 2 synthesis, which may lead to high performance in both activity and selectivity.…”

“…As the Au content increased, the number of Pd domains decreased, while that of Au domains increased. Because Au surfaces are inactive for H 2 dissociation, which is necessary for direct H 2 O 2 synthesis, , only the exposed Pd surfaces primarily contributed to the H 2 conversion. Thus, it is understood that the H 2 conversion on Pd–Au NPs decreases with increased Au content.…”

“…21−24 The Pd domains can facilitate the H 2 conversion process. 24,25 (controlling the ratio of the three exposure regions) is an important challenge. In this work, to understand the catalytic performance of this new category of bimetallic NP catalysts (namely, nonconcentric NPs), we synthesized nonconcentric Pd−Au NPs based on a previous procedure.…”