第一作者：Lei Huang, Ya-Qiong Su, Dai Dang
通訊作者：Bao Yu Xia
通訊單位：華中科技大學(xué)
研究?jī)?nèi)容：
作者在此報(bào)告了一種通過(guò)集成工程封裝石墨碳的多孔富鉑合金，其中三元PtCuCo合金和石墨Co-N-C之間的協(xié)同催化可優(yōu)化反應(yīng)路徑并改善氧還原反應(yīng)（ORR）性能。催化劑PtCuCo@Co-N-C在0.9 V（vs RHE)下，質(zhì)量活性為1.14 A mgPt-1。在全電池評(píng)估中，RHEPT的峰值功率密度為960mW/cm2，優(yōu)于商用Pt/C催化劑（0.12 A mgPt-1和780 mW/cm2）。實(shí)驗(yàn)結(jié)果與理論模擬相結(jié)合表明，多孔Pt合金與Co-N-C之間的相互作用是提高催化性能的原因。這種集成工程概念對(duì)于增強(qiáng)鉑基催化劑的抗腐蝕能力和改善其ORR性能具有重要意義。
要點(diǎn)一：
之前大量的研究集中于將Pt與過(guò)渡金屬(Ni, Co, Cu等)合金化，以調(diào)節(jié)Pt的電子結(jié)構(gòu)，降低Pt的消耗。然而，由于催化劑和載體的腐蝕和團(tuán)聚行為，它們?nèi)匀粫?huì)出現(xiàn)嚴(yán)重的性能退化和快速的使用失效，而含有過(guò)渡金屬-氮-碳(M-N-C)基團(tuán)的缺陷納米碳具有豐富的催化位點(diǎn)，且高度石墨化，這可以促進(jìn)一定的催化活性，并加速ORR上的電荷轉(zhuǎn)移。
要點(diǎn)二：
作者報(bào)道了用于高效ORR電催化的PtCuCo@Co-N-C雜化催化劑的制備。通過(guò)集成工程制備的缺陷碳覆蓋富鉑多孔合金增強(qiáng)了ORR活性、耐蝕性和結(jié)構(gòu)穩(wěn)定性，其中三元PtCuCo合金與石墨Co-N-C之間的協(xié)同現(xiàn)象提供了優(yōu)化的反應(yīng)路徑和更強(qiáng)的相互作用。此外，多孔的PtCuCo合金和碳網(wǎng)有助于氧的運(yùn)輸和活性位點(diǎn)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.
參考文獻(xiàn)：
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.
