Lin Fangxu, Lv Fan, Zhang Qinghua, Luo Heng, Wang Kai, Zhou Jinhui, Zhang Weiyu, Zhang Wenshu, Wang Dawei, Gu Lin, Guo Shaojun
School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Adv Mater. 2022 Jul;34(27):e2202084. doi: 10.1002/adma.202202084. Epub 2022 May 31.
Moderate adsorption of oxygenated intermediates takes a significant role in rational design of high-efficiency oxygen reduction reaction (ORR) electrocatalysts. Long-serving as a reliable strategy to tune geometric structure of nanomaterials, defect engineering enjoys the great ability of adjusting the coordination environment of catalytic active sites, which enables dominant regulation of adsorption energy and kinetics of ORR catalysis. However, limited to controllable nanocrystals fabrication, inducing uniformly dispersed high-coordinated defects into ultrathin 2D nanosheets remains challenging. Herein, atomic-scale cavities (ASCs) are proposed as a new kind of high-coordinated active site and successfully introduced into suprathin Pd (111)-exposed metallene. Due to its atomic concave architecture, leading to elevated CN and moderately downshifted d-band center, the as-made Pd metallene with ASCs (c-Pd M) exhibits excellent ORR performance with mass activity of 2.76 A mg at 0.9 V versus reversible hydrogen electrode (RHE) and half-wave potential as high as 0.947 V, which is 18.9 (2.7) times higher and 104 (46) mV larger than that of commercial Pt/C (Pd metallene without ASCs). Besides, the durability of c-Pd M exceeds its commercial counterpart with ≈30% loss after 5000 cycles. This work highlights a new-style mentality of designing fancy active sites toward efficient ORR electrocatalysis.
含氧中间体的适度吸附在高效氧还原反应（ORR）电催化剂的合理设计中起着重要作用。缺陷工程长期以来一直是调节纳米材料几何结构的可靠策略，它具有强大的调节催化活性位点配位环境的能力，能够主导调节ORR催化的吸附能量和动力学。然而，限于可控纳米晶体的制备，在超薄二维纳米片中引入均匀分散的高配位缺陷仍然具有挑战性。在此，原子尺度空腔（ASCs）被提出作为一种新型的高配位活性位点，并成功引入到超薄的暴露Pd（111）的金属烯中。由于其原子凹面结构，导致配位数升高和d带中心适度下移，所制备的具有ASCs的Pd金属烯（c-Pd M）表现出优异的ORR性能，在相对于可逆氢电极（RHE）的0.9 V下质量活性为2.76 A mg，半波电位高达0.947 V，分别比商业Pt/C（无ASCs的Pd金属烯）高18.9（2.7）倍和大104（46）mV。此外，c-Pd M的耐久性超过其商业对应物，在5000次循环后损失约30%。这项工作突出了一种设计奇特活性位点以实现高效ORR电催化的新型思路。
