Key laboratory of Material Chemistry for Energy Conversion and Storage (Huazhong University of Science and Technology), Ministry of Education, Hubei Key Laboratory of Material Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P.R. China.
Nanoscale. 2016 Aug 21;8(31):14793-802. doi: 10.1039/c6nr03944h. Epub 2016 Jul 22.
Exploring highly active, stable and relatively low-cost nanomaterials for the oxygen reduction reaction (ORR) is of vital importance for the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, a highly active, durable, carbon supported, and monolayer Pt coated Pd-Co-Zn nanoparticle is synthesized via a simple impregnation-reduction method, followed by spontaneous displacement of Pt. By tuning the atomic ratios, we obtain the composition-activity volcano curve for the Pd-Co-Zn nanoparticles and determined that Pd : Co : Zn = 8 : 1 : 1 is the optimal composition. Compared with pure Pd/C, the Pd8CoZn/C nanoparticles show a substantial enhancement in both the catalytic activity and the durability toward the ORR. Moreover, the durability and activity are further enhanced by forming a Pt skin on Pd8CoZn/C nanocatalysts. Interestingly, after 10 000 potential cycles in N2-saturated 0.1 M HClO4 solution, Pd8CoZn@Pt/C shows improved mass activity (2.62 A mg(-1)Pt) and specific activity (4.76 A m(-2)total), which are about 1.4 and 4.4 times higher than the initial values, and 37.4 and 5.5 times higher than those of Pt/C catalysts, respectively. After accelerated stability testing in O2-saturated 0.1 M HClO4 solution for 30 000 potential cycles, the half-wave potential negatively shifts about 6 mV. The results show that the Pt skin plays an important role in enhancing the activity as well as preventing degradation.
探索高效、稳定且相对低成本的纳米材料对于质子交换膜燃料电池（PEMFC）的商业化至关重要。在此，通过简单的浸渍-还原法合成了一种高活性、长寿命、负载于碳上且单层 Pt 包覆的 Pd-Co-Zn 纳米颗粒，随后发生了 Pt 的自发取代。通过调整原子比，我们获得了 Pd-Co-Zn 纳米颗粒的组成-活性火山曲线，并确定 Pd:Co:Zn=8:1:1 为最佳组成。与纯 Pd/C 相比，Pd8CoZn/C 纳米颗粒在 ORR 的催化活性和耐久性方面都有显著提高。此外，通过在 Pd8CoZn/C 纳米催化剂上形成 Pt 壳，进一步提高了其耐久性和活性。有趣的是，在 N2 饱和的 0.1 M HClO4 溶液中经过 10000 个电位循环后，Pd8CoZn@Pt/C 表现出更高的质量活性（2.62 A mg-1Pt）和比活性（4.76 A m-2总），分别是初始值的 1.4 倍和 4.4 倍，以及 Pt/C 催化剂的 37.4 倍和 5.5 倍。在 O2 饱和的 0.1 M HClO4 溶液中加速稳定性测试 30000 个电位循环后，半波电位负移约 6 mV。结果表明，Pt 壳在提高活性和防止降解方面发挥了重要作用。
