Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates

Abstract

Oxygen reduction reaction towards hydrogen peroxide (H2O2) provides a green alternative route for H2O2 production, but it lacks efficient catalysts to achieve high selectivity and activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm−2) while maintaining high H2O2 selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H2O2 activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H2O2 solutions with high selectivity (up to 95%) and high H2O2 partial currents (up to ~400 mA cm−2), illustrating the catalyst’s great potential for practical applications in the future.

High Activity and Selectivity of M-N/C Catalysts toward Two-Electron O2 Electroreduction

“…and 138 mV dec -1 , respectively. The higher the Tafel slope, the faster the overpotential increases with current density [23]. Tafel slopes that significantly exceed 120 mV dec -1 are generally an indication that there are mass transfer problems that confound the kinetics mV dec -1 and 100 mV dec -1 , respectively.…”

“…Tafel slopes that significantly exceed 120 mV dec -1 are generally an indication that there are mass transfer problems that confound the kinetics mV dec -1 and 100 mV dec -1 , respectively. For these materials, a slope below 120 mV dec -1 indicates that the electrochemical reaction is capable of obtaining a high current density with low potential [23].…”

Oxygenated boron-doped carbon via polymer dehalogenation as an electrocatalyst for high-efficiency O2 reduction to H2O2

“…S12, the 2e − ORR catalytic activity of the O-BC materials increases with annealing temperature from 550 to 650°C, with O-BC-2-650 exhibiting the highest H 2 O 2 selectivity; when the temperature exceeds 650°C (i.e., O-BC-2-700), the 4e − ORR pathway is promoted. The excellent H 2 O 2 selectivity of O-BC-2-650 can be attributed to its abundance of doped boron sites and porous structure [19,31]. The electrochemical stability of O-BC-2-650 was investigated by the steady-state polarization method.…”

“…In addition to the above-mentioned heteroatom dopants, boron has a lower electronegativity (2.04) than that of carbon (2.55). Thus, a B site is positively charged when situated adjacently to a C site, facilitating the chemisorption of O 2 molecules and promoting the ORR at B instead of nearby C sites [29][30][31]. Nevertheless, the use of self-initiative heteroatom dopants like B to promote the 2e − ORR remains relatively under researched.…”

Extended Conjugation Refining Carbon Nitride with Thermodynamically Boosted Photocatalytic H2O2 Production and Application for Hypoxic Tumor Therapy

“…Although plenty of pioneering studies investigating H2O2 production in several particulate systems have been reported, such as foreign chemical doping, surface defects controlling, various heterogenization and molecular architecture modulation, most of them still exhibited general, relatively poor efficiencies of H2O2 production [6][7][8][18][19][20][21] . The ineffective hole scavenging via water oxidation and the resulting charge recombination often necessitates the addition of organic electron donors [22,23] . Besides, low selectivity toward H2O2 synthesis via twoelectron O2 reduction compared to the four-electron reduction of O2 or two-electron H2 evolution required manipulating noble metallic sites as cocatalysts to improve both the activity and selectivity of H2O2 production [19,[24][25][26] .…”