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

Abstract

The direct electrochemical synthesis of H 2 O 2 from O 2 is currently the most promising alternative to energyintensive industrial anthraquinone oxidation/reduction methods. However, its widespread use is hampered by the lack of efficient low-cost electrocatalysts. In the current study, oxygenated boron-doped carbon (O-BC) materials were realized via a green synthetic strategy involving polymer dehalogenation and employed as electrode materials for the electrochemical synthesis of H 2 O 2 via a 2e − oxygen reduction. The catalytic activity of the O-BC materials was optimized through systematic variation of the boron source (H 3 BO 3 ) dosage and annealing temperature. Electrochemical measurements revealed that the optimal sample (O-BC-2-650) exhibited a selectivity of 98% for the 2e − oxygen reduction to H 2 O 2 and an average H 2 O 2 production rate of 412.8 mmol g cat. −1 h −1 in an H-type alkaline electrolyzer. Density functional theory simulations indicated that the functionalization of active B sites with one oxygen atom provides the lowest Gibbs free energy change (ΔG) of 0.03 eV for the hydrogenation of * O 2 , while functionalization with zero or two O atoms results in much larger ΔG values (0.08 and 0.10 eV, respectively). Thus, this work details a new type of green, lowcost, and metal-free electrocatalyst for H 2 O 2 production.

Ultrahigh oxygen-doped carbon quantum dots for highly efficient H2O2 production via two-electron electrochemical oxygen reduction

“…530 eV and 281 eV corresponding to O 1s and C 1s, respectively. 50,51 Note that the O 1 s peak is stronger than the C 1s peaks for the CQD sample and the atomic oxygen-to-carbon ratio reaches 30.4 : 69.6, much higher than those of the CSs and the rGQDs and other reported works. 18,19,42 This suggests the ultrahigh O content existing in the CQD samples.…”

Steering Carbon Hybridization State in Carbon-Based Metal-free Catalysts for Selective and Durable CO2 Electroreduction

“…In terms of the B chemical environment, in addition to the effect of B−C and B−N as presented in Figure 2c, the presence of B−O bonding signifies the possible coordination structure of O-BC 2 , which may derive from the point defect upon B doping. 56,57 Such an effect was further studied by DFT calculations. Considering that the B active site is bonded with the N atom, based on the B,Ndoped sp 3 /sp 2 hybrid model, we employ one graphitic N atom equivalent to one C atom to construct the O−BCN structure to represent the point defect model (Figure S16), 58 which is denoted as B,N-doped sp 3 /sp 2 hybrid-v.…”

“…Compared with the B,N-doped sp 3 /sp 2 hybrid (Figure f), the N-doped sp 3 /sp 2 hybrid exhibits a higher energy barrier for the formation of *OCHO and a much smaller energy difference between *OCHO and *COOH (Figure S15b), resulting in inferior HCOOH selectivity, which is consistent with the experimental results (Figure S11). In terms of the B chemical environment, in addition to the effect of B–C and B–N as presented in Figure c, the presence of B–O bonding signifies the possible coordination structure of O-BC 2 , which may derive from the point defect upon B doping. , Such an effect was further studied by DFT calculations. Considering that the B active site is bonded with the N atom, based on the B,N-doped sp 3 /sp 2 hybrid model, we employ one graphitic N atom equivalent to one C atom to construct the O–BCN structure to represent the point defect model (Figure S16), which is denoted as B,N-doped sp 3 /sp 2 hybrid-v.…”

Oxygenated P/N co-doped carbon for efficient 2e−oxygen reduction to H2O2

“…28 Recently, it is found that introducing oxygen-containing groups into carbon can effectively tune the ORR pathway from 4e À to 2e À , implying the possibility of efficient production of H 2 O 2 from O 2 or air, [29][30][31] for instance, O-doped CNTs reported by Cui group, 30 and O-doped carbon nanosheets reported by Liu group. 32 Among all DCMs, N, P co-DCMs typically drive the 4e ORR, as conrmed by many state-of-the-art studies, including the NPMC reported by Dai's group, 33 NPC-4-1100-Zn reported by Xing's group, 34 etc. How to tune the ORR occurring on N, P co-DCMs into the 2e À pathway is intriguing and yet to be explored.…”