1成果简介
氯碱工艺在全球化工领域具有不可替代的作用，但其对RuO?（或IrO?）/TiO?基尺寸稳定阳极的高度依赖，阻碍了该工艺的可持续发展及新应用拓展。本文，中国科学院合肥物理研究所尹华杰 研究员、Huijun Zhao等在《 J. Am. Chem. Soc》期刊发表名为“Oxygenated Carbon Electrocatalysts for Chlorine Evolution Reaction”的论文，研究提出一种简便的氧活化方法，可在商用炭黑和碳布上生成适宜的氧官能团。实验与理论研究表明，在石墨平面边缘引入羰基、环状醚及羧基官能团后，商用碳材料展现出卓越的氯气析出反应活性（过电位：1 A cm–2时达204 mV）、选择性 （平均法拉第效率：99.6 ± 1.3%）及稳定性（在0.5 A cm–2下稳定运行100小时），其性能可媲美甚至超越基准RuO2及尺寸稳定阳极。
2图文导读
图1. Synthetic procedure and characterization of O-BP. (a) Schematic illustrating the fabrication of O-BP via annealing. SEM (b) and TEM (c) images of O-BP nanoparticles. (d) N2 adsorption–desorption isotherm and pore-size distribution (inset) of O-BP. (e) XPS survey spectrum and high-resolution O 1s XPS spectrum (inset) of O-BP. (f) Proposed oxygenation structure of the O-BP graphitic plane.
图2. CER performance. (a) LSV curves of O-BP, BP, commercial RuO2, and graphite rod in 4 M NaCl (pH = 1) at a scanning rate of 5 mV s–1. (b) Tafel plots of O-BP, RuO2, and BP. (c) CV curves of O-BP. Black line: without correction; red line: with 95% iR correction. (d) Chronopotentiograms of O-BP and graphite rod in 4.0 M NaCl (pH = 1) at a current density of 0.5 A cm–2. O-BP, BP, and commercial RuO2 are supported on carbon paper with a loading density of 2 mg cm–2.
图3. CER activities of different oxygen functional groups. (a) Structural models of oxygen-containing sites on edges of monolayer armchair chrysene graphene and zigzag tetracene graphene examined in this study. Golden, red, and white circle represent carbon, oxygen, and hydrogen atoms, respectively. (b) CER free energy diagrams of representative sites in oxygenated carbon and RuO2 at zero overpotential. (c) Relationship between ΔG*Cl and Dpz@EF. (d) PDOS of pz around the Fermi level and charge density difference of graphene, C5/C=OZG and C5/OHZG with the adsorbed *Cl. Cyan stands for holes and yellow for electrons. The isosurfaces are taken as 0.005e per Bohr。
图4. Effect of intrinsic and extrinsic properties of O-BP on CER performance and O–CC-catalyzed CER under industry operating current densities. (a–c) Theoretical trends of CER overpotential under 1 A cm–2 with variation in electrochemically active surface area and TS free energy of catalysts for given α of 0.58 (a, O-BP), 0.47 (b, BP), and 0.43 (c, graphite rod), respectively. (d) LSV curves recorded from chlor-alkali cells assembled using O–CC, CC, and commercial DSA, respectively, as the anode and 20 wt % Pt/C (supported on carbon paper) as the cathode at room temperature in 4.0 M NaCl (pH = 1) anolyte and 6 M NaOH catholyte. Electrode area: 1 × 1 cm2; inset: photograph of O–CC. (e) Chronopotentiogram and corresponding Faradaic efficiency of O–CC∥Pt/C chlor-alkali cell at 0.5 A.
3小结
总体而言，研究表明，通过构建适宜的含氧碳位点，长期被忽视的碳基材料可作为与RuO?/DSA相当的高性能CER电催化剂。我们示范了一种简便的退火氧化的方法，可在商用炭黑和碳布上形成适宜的氧官能团。实验与理论结果均验证：在石墨平面边缘构建羰基、环状醚及羧基结构，可赋予氧化的碳材料卓越的氯气进化催化活性与稳定性。经活化的含适配氧基团的商用BP材料，能在极低氯气进化过电位下实现高电流密度，并保持近100%的法拉第效率与稳定性。相较于传统贵金属催化剂，本文展示的含氧碳电催化剂在实验室及模拟工业规模下均展现出更优异的氯气析出活性与稳定性，为大规模海水电解及脱盐盐水处理领域制造新一代阳极提供了极具前景的绿色生产解决方案。
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