Solid Phase Synthesis And Electrocatalytic Two-electron Oxygen Reduction Of Modified Carbon-based Materials

The electrocatalytic two-electron oxygen reduction（2eORR）is an environmental-friendly,safety,reliability and high efficiency method for the hydrogen peroxide（H₂O₂）production compared with the traditional industrial anthraquinone method.In this paper,carbon material（Ketjen black,KB）was modified by the strategies of surface oxidation and boron nitrogen doping.Then,the effect of modification carbon-based materials on the selectivity of H₂O₂ through 2eORR were studied by the microstructure and composition of the electrocatalysts.The specific research contents are as follows:Firstly,we use the oxidation and reduction methods to treat KB,oxidized carbon（KB-ox）and reduced carbon（KB-Re）were obtained respectively.Then,we discussed the differences in compositions and structures of KB-Ox and KB-Re.The KB-Ox has the highest O content（2.1%）and highest surface acidity.In addition,the 2eORR selectivity of KB-OX is 87.5%,obviously higher than KB-Re（47%）.KB-Ox also exhibited a good catalytic stability of 8 h H₂O₂ production with faraday efficiency above 80%.The similar improvements of catalytic performances are also applicable to Super-P and graphite carbon.Secondly,boron nitrogen co-doped carbon material（BCN-1100）was synthesized by KB and boron nitride（BN）through high temperature solid state reaction.BCN-1100demonstrated an excellent 2eORR selectivity（89%）and catalytic stability（only current density of 0.12 m A/cm² decreased after 15000 cycles of cyclic voltammetry）.Then,the calcination temperatures are discussed,the distribution and concentration of B and N in the carbon framework were proved as the key to their catalytic activity.Theoretical calculations reveal that BNC₂ configuration is an ideal two-electron reactive center with the suitable*OOH adsorption energy.Thirdly,we discussed the high temperature solid phase synthesis of sodium borohydride（Na BH₄）,urea and KB.high ratios of B,N and O doped carbon（H-BNO-KB）could be synthesized by controlling the process of calcination temperature.Scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）analysis showed that the generation of carbon nitride（C₃N₄）at 550℃from urea is benefit to obtain high B,N and O content materials.The atom ratios of B,N and O in H-BNO-KB were 11.66%,4.87%and 10.72%,respectively.Which is significantly higher than BNO-KB.H-BNO-KB exhibits an excellent 2eORR selectivity of 85.6%and a great catalytic stability.