Rational Design of Metal-free Doped Carbon Nanohorn Catalysts for Efficient Electrosynthesis of H₂O₂ from O₂ Reduction

Abstract

Electroreduction of O2 is a promising method for decentralized H2O2 production. Due to their high selectivity, low cost, and highly tunable properties, O- and N-doped carbon catalysts are appealing for this process. However, the relative effects of O and N dopants on the catalytic performances of carbon are not well understood. In this work, we present highly active and selective 2e– O2 reduction catalysts based on doped carbon nanohorns (CNH) synthesized by the gas-injected arc-in-water (GI-AIW) method. The effects of O and N dopants incorporated during the synthesis and the post-treatment are investigated. We discovered that the selectivity of CNH may be more sensitive to changes in N dopant than to changes in O dopant. Our doped CNH catalyst exhibits an early onset potential of 0.85 V vs RHE, >80% selectivity, and excellent stability even after 5,000 cycles and 12 h of flow electrolysis. Our gas diffusion device can generate H2O2 at a practical concentration of 56 mM per hour, corresponding to a production rate of 0.74 mol h–1 gcat –1. These results suggest that regulating both O and N dopants is an effective design strategy for an efficient carbon catalyst, which is essential in the electrosynthesis of H2O2 from O2.

High-Surface-Area Graphene Oxide for Next-Generation Energy Storage Applications

“…In graphene-like materials, the number of stacking layers has a great impact on the 2D-band shape but also on its intensity, which decreases with an increasing number of layers. , In the present case, the effect mentioned above is observed for samples oxidized under more harsh conditions. Also, a gradual shift of the D- and 2D bands is systematically observed toward higher frequencies with the increase of the H 2 O 2 concentration (Figure a,b), in qualitative agreement with the acceptor action (hole doping) of the oxygen functional groups. ,, Changes in various functional group formationsdetermined by thermal analysis (see Figure S5) and distributioncorrelates with the Raman G-band FWHM as well as S BET of the studied samples (Figure S5). A higher relative amount of more thermally stable surface groups, a higher surface area, and G-band FWHM are observed.…”

“…Also, a gradual shift of the D-and 2D bands is systematically observed toward higher frequencies with the increase of the H 2 O 2 concentration (Figure 6a,b), in qualitative agreement with the acceptor action (hole doping) of the oxygen functional groups. 30,32,33 Changes in various functional group formations�determined by thermal analysis (see Figure S5) and distribution�correlates with the Raman G-band FWHM as well as S BET of the studied samples (Figure S5). A higher relative amount of more thermally stable surface groups, a higher surface area, and G-band FWHM are observed.…”

“…However, under more drastic conditions, it increases again due to the removal of less-organized (more reactive) carbon (Table S2). 32 Elemental analysis also shows gradual composition changes (Table S2). The raw material has the lowest oxygen concentration among the studied materials.…”

General Pyrolysis for High-Loading Transition Metal Single Atoms on 2D-Nitro-Oxygeneous Carbon as Efficient ORR Electrocatalysts

“…The current collection efficiency of the Pt ring (N) was determined to be 0.254, according to the reduction of K 3 Fe[CN] 6 . 60 The Koutecky−Levich (K−L) equation (eq 3) 61 was used to calculate the ORR kinetics.…”

Catalytic Hot-Electron SERS Analytical Substrates and a Case Study on Graphene Nanocomposite Inspection

“…Energetic electron transfer across an interface between two media is potentially useful in a number of critical technologies such as electric generation, − sensor, − and on-surface chemical transformation. , In particular, the interfacial transfer of hot electrons, each of which stores an energy of ∼1 to 3 eV above the Fermi level at room temperature, , from the electrode surface into the adsorbate can enable various chemical reactions inaccessible via other catalytic processes. − Similarly, such electrochemistry is instrumental in developing charge-transfer (CT) surface-enhanced Raman spectroscopy (SERS), which uses electron transfer between the SERS substrate and the adsorbate to enhance the Raman signal intensity of the adsorbed molecule for efficient chemical detection. − Thus, the ability to realize the parameters determining the transfer of hot charge carriers is fundamentally important to electrode design and utilization.…”