第一作者：Lei Huang, Ya-Qiong Su, Dai Dang
通讯作者：Bao Yu Xia
通讯单位：华中科技大学
研究内容：
作者在此报告了一种通过集成工程封装石墨碳的多孔富铂合金，其中三元PtCuCo合金和石墨Co-N-C之间的协同催化可优化反应路径并改善氧还原反应（ORR）性能。催化剂PtCuCo@Co-N-C在0.9 V（vs RHE)下，质量活性为1.14 A mgPt-1。在全电池评估中，RHEPT的峰值功率密度为960mW/cm2，优于商用Pt/C催化剂（0.12 A mgPt-1和780 mW/cm2）。实验结果与理论模拟相结合表明，多孔Pt合金与Co-N-C之间的相互作用是提高催化性能的原因。这种集成工程概念对于增强铂基催化剂的抗腐蚀能力和改善其ORR性能具有重要意义。
要点一：
之前大量的研究集中于将Pt与过渡金属(Ni, Co, Cu等)合金化，以调节Pt的电子结构，降低Pt的消耗。然而，由于催化剂和载体的腐蚀和团聚行为，它们仍然会出现严重的性能退化和快速的使用失效，而含有过渡金属-氮-碳(M-N-C)基团的缺陷纳米碳具有丰富的催化位点，且高度石墨化，这可以促进一定的催化活性，并加速ORR上的电荷转移。
要点二：
作者报道了用于高效ORR电催化的PtCuCo@Co-N-C杂化催化剂的制备。通过集成工程制备的缺陷碳覆盖富铂多孔合金增强了ORR活性、耐蚀性和结构稳定性，其中三元PtCuCo合金与石墨Co-N-C之间的协同现象提供了优化的反应路径和更强的相互作用。此外，多孔的PtCuCo合金和碳网有助于氧的运输和活性位点暴露，提高ORR。
Scheme 1. Preparation illustration of the porous PtCuCo@Co-N-C hybrid catalyst.
Figure 1. (a) SEM, (b) TEM, (c) HAADF-STEM, (d) HRTEM, (e) ACTEM, inset is FFT pattern, (f) AC-STEM images, (g) EDS line scanning, (h) EDS spectrum, (i) EDS mapping of the PtCuCo@Co-N-C catalyst.
Figure 2. (a) XRD patterns, (b) N 1s, and (c) Pt 4f XPS spectra of PtCuCo@Co-N-C. (d) XANES, (e) Fourier transforms of EXAFS spectra and (f) WT diagram for the Pt L3-edge. (g) XANES, (h) Fourier transforms of EXAFS spectra and (i) WT analysis for the Co K-edge.
Figure 3. (a) LSV curves and corresponding electron transfer number, (b) Tafel plots, (c) half-wave potential and mass activity at 0.9 V vs. RHE of Pt/C, PtCu, Co-N-C and PtCuCo@Co-N-C. (d) CV profiles, (e) LSV curves, and (f) other activity changes of PtCuCo@Co-N-C before and after 50,000 cycles. (g) LSV profiles (inset is CV curves) of Pt/C before and after 10,000 cycles. (h) Polarization plots of hydrogen-air fuel cells with Pt/C and PtCuCo@Co-N-C as cathode catalysts. (i) Stability test of hydrogen-air fuel cell at a voltage of 0.6 V.
Figure 4. (a) Schematic diagram of the ORR pathways of PtCuCo@Co-N-C. (b, c) Free energy and synergetic mechanism of PtCuCo(111) and Co-N-C sites.
参考文献：
Xia B Y. Boosting Oxygen Reduction via Integrated Construction and Synergistic Catalysis of Porous Platinum Alloy and Defective Graphitic Carbon [J]. Angew Chem Int Ed Engl, 2021, doi.org/10.1002/anie.202111426.
