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As a versatile and environmentally friendly chemical, hydrogen peroxide (H2O2) is in high demand. The current anthraquinone oxidation process suffers from high energy consumption in hydrogen production and the cumbersome alternating operations of hydrogenation and oxidation. The direct synthesis of H2O2 from H2 and O2 is constrained by the balance between safety and efficiency and heavy metal pollution from catalysts. Two-electron oxygen reduction reaction (2e− ORR) is an efficient, safe, and low-cost route for the production of H2O2. This 2e− ORR pathway has potential to become a supplement to the anthraquinone process because of fossil energy-free feature. The bottleneck of the industrialization of 2e− ORR is the lack of efficient catalysts. The 2e− ORR catalytic performance of noble metal electrode materials urgently needs to be significantly enhanced by smart design. However, the high price and limited reserves of these noble metal-based materials still severely limit their commercialization. Among many 2e− ORR catalysts, carbon-based catalysts have received much attention because of their low cost and diverse structures. This study reviews the research progress and the synthesis methods of carbon-based catalysts for 2e− ORR in recent years. First, this paper introduces the fundamental mechanism of H2O2 production by 2e− ORR through a combination of theory and experiment. Then, the synthesis methods and optimization strategies of various high-efficiency carbon-based catalysts are discussed. Finally, the various influencing factors (pH effect, pore structure, and carbon defects) and the practical applications for H2O2 production are analyzed. In addition, the future research direction is also proposed to promote the development of carbon-based catalysts for 2e− ORR toward industrialization. Although carbon-based catalysts display obvious advantages for electrocatalytic applications, there are still a few shortcomings that need to be overcome. The intrinsic activity and the long-term stability of carbon-based materials still require to be improved to a level that can be compared with those of noble metal-based catalysts. This review presents a comprehensive overview of the latest developments in the production of H2O2 by 2e− ORR on carbon-based catalysts, combining the most advanced theoretical and experimental literature available. The current state of the research on carbon-based catalysts in recent years indicates great promise for further advancement. [ABSTRACT FROM AUTHOR]

The large-scale applications of zinc–air batteries (ZABs) as vital energy storage devices have been limited by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the air electrode. Herein, Mn-doped Co nanoparticles on cedarwood-derived carbon (CoMn-N@NCW) are fabricated as a bifunctional catalyst to boost the reaction kinetics. The as-prepared catalyst shows a half-wave potential of 0.885 V for the ORR and an overpotential of 335 mV at 10 mA cm−2 for the OER in alkaline electrolytes. ZABs based on the catalyst exhibit a high peak power density of 186 mW cm−2 and a robust lifetime of 600 h. The quasi-solid-state ZABs assembled with CoMn-N@NCW exhibit a splendid open-circuit voltage of 1.493 V and a long-term cycling stability of 70 h. Oxygen electrocatalytic kinetics are improved by the electronic modulation of cobalt from adjacent manganese and the rapid mass transfer of porous biomass carbon. This work provides a remarkable inspiration to prepare a practically applicable oxygen electrode for ZABs. [ABSTRACT FROM AUTHOR]

Advances in rechargeable zinc–air batteries are hindered by the lack of efficient and economical oxygen electrocatalysts. Herein, a monolithic bifunctional catalyst is rationally constructed via an in situ growth of a FeNi3 alloy on nitrogen-doped wood-derived carbon (FeNi3@NWC). FeNi3 alloy nanoparticles coupled with nitrogen-doped carbon expedite the catalytic activity toward oxygen reduction reaction (ORR) by promoting proton generation on FeNi3 and transfer to nitrogen-doped carbon. The actual formation of Ni1–xFexOOH on the surface of the FeNi3 alloy effectively accelerates oxygen evolution reaction (OER) via the charge transfer with outstanding activity. The potential gap of only 0.68 V between ORR and OER of FeNi3@NWC is achieved. The liquid zinc–air batteries (ZABs) with FeNi3@NWC convey a robust lifetime of ∼266 h (800 cycles) with stable charging and discharging. Theoretical calculations manifest that the construction of double active sites through a synergistic mechanism between the FeNi3 alloy and catalytically active carbon ignites the prominent catalytic activity with superior stability. This work provides remarkable inspiration for the rational design of biomass-derived efficient electrocatalysts and will facilitate the practical application of energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

TiO2-pillared layered niobic acid was prepared through a stepwise ion-exchange route, in which n-decylamine-pre-swelled layered niobic acid was subjected to react with the pillaring solution containing Ti(IV) polycations obtained by using tetrabutyl titanate as titanium source; then, the as-synthesized Ti(IV) polycation-intercalated layered intermediate was calcined at 723 K in air atmosphere. Powder XRD, FT-IR, SEM, and DR-UV–Vis techniques were employed to characterize the structure and photo-absorption property of the TiO2-pillared layered niobic acid products and their precursors. The catalytic performance of the TiO2-pillared layered products for photodegradation reaction of rhodamine B under ultraviolet light irradiation was also evaluated. The laws of Ti(IV) pillaring solution concentration affecting on the intercalating behavior of Ti(IV) polycations in layered niobic acid, and on the structure and photocatalytic performance of the final TiO2-pillared layered products were revealed. Compared with pure TiO2 or un-pillared layered niobic acid, the binary TiO2-pillared layered niobic acid product exhibited an excellent catalytic activity for the photodegradation reaction of rhodamine B. [ABSTRACT FROM AUTHOR]

The intercalation behaviour of titanium(IV) (triethanolaminato)-isopropoxide (abbreviated as TEAIP) in a series of layered protonic metal oxides was investigated. Two novel inorganic–organic hybrid nanocomposites have been obtained. [Copyright &y& Elsevier]

TiO2-pillared layered niobic acid was prepared through a stepwise ion-exchange route, in which n-decylamine-pre-swelled layered niobic acid was subjected to react with the pillaring solution containing Ti(IV) polycations obtained by using tetrabutyl titanate as titanium source; then, the as-synthesized Ti(IV) polycation-intercalated layered intermediate was calcined at 723 K in air atmosphere. Powder XRD, FT-IR, SEM, and DR-UV–Vis techniques were employed to characterize the structure and photo-absorption property of the TiO2-pillared layered niobic acid products and their precursors. The catalytic performance of the TiO2-pillared layered products for photodegradation reaction of rhodamine B under ultraviolet light irradiation was also evaluated. The laws of Ti(IV) pillaring solution concentration affecting on the intercalating behavior of Ti(IV) polycations in layered niobic acid, and on the structure and photocatalytic performance of the final TiO2-pillared layered products were revealed. Compared with pure TiO2 or un-pillared layered niobic acid, the binary TiO2-pillared layered niobic acid product exhibited an excellent catalytic activity for the photodegradation reaction of rhodamine B. [ABSTRACT FROM AUTHOR]

Palladium-based catalysts are remarkable in endorsing hydrogen (H 2 ) generation through formic acid (HCOOH, FA) dehydrogenation under near-ambient conditions. Hydrogen energy efficiency depends on high-performance catalyst design. In this study, Pd-Cu nanoalloy catalysts with mutable atomic ratios are successfully fabricated on TiO 2 nanosheets (TiO 2 -NSs).The synergistic electronic interactions between Palladium (Pd) and copper (Cu) are revealed through a density of states (DOS) analysis of alloy supported over a mixed valence state of Ti linked to oxygen vacancies (Vo) in TiO 2 -NSs, Enhanced adsorption of target molecules reveals novel active sites for Formic acid dehydrogenation (FAD), with O─H bond cleavage via HCOO formate intermediate preceding C─H and C─O bond cleavage. Experimental and theoretical research demonstrates that the Pd-Cu/TiO 2 -NSs (3:7) catalyst d electron redistribution and d-band center shift lower the activation energy for O─H bond cleavage, exhibit superior H 2 production than pure Pd and Cu, increasing Pd electron density due to synergistic effects from reactive crystal facets, defects, and strong metal support interactions (SMSI), lowering the activation energy for HCOOH dissociation step, generating carbon dioxide (CO 2 ) and H 2 with a unprecedented high turnover frequency (TOF) of 6268 mol H2 .h -1 .molPd -1 at 303K with activation energy (E a ) of 15 KJ mol -1 . This attempt models an efficient HCOOH-to-hydrogen catalyst., (© 2024 Wiley‐VCH GmbH.)