Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, China.
Nanoscale. 2018 Jul 13;10(27):12975-12980. doi: 10.1039/c8nr03350a.
The development of high-performance non-precious electrocatalysts for both H2 and O2 evolution reactions (HER and OER activities) and overall water splitting is highly desirable but remains a grand challenge. Herein, we report a facile method to synthesize ultrathin, amorphous, porous, oxygen and defect enriched NiCoFe phosphate nanosheets (NSs). Owing to their microporous confinement in a 2D orientation, which can reduce the ion transport resistance during electrochemical processes, and defect enriched structure with higher electrochemically active surface area, these NiCoFe phosphate porous nanosheets supported on nickel foam (NiCoFe phosphate NSs/NF) facilitate the diffusion of gaseous products (H2 and O2) and exhibit remarkable catalytic performance and outstanding stability for both HER, OER and overall water splitting in an alkaline electrolyte (1.0 M KOH). For the OER electrocatalyst, 2D NiCoFe phosphate NSs/NF was oxidized to NiCoFe oxides/hydroxides on the catalyst surface and exhibited remarkable OER activity with a low overpotential of only 240 mV needed to reach a current density of 10 mA cm-2. For HER, 2D NiCoFe phosphate NSs/NF afforded a current density of 10 mA cm-2 at a low overpotential of only -231 mV. Furthermore, employing 2D NiCoFe phosphate NSs/NF as the electrocatalyst for both the anode and the cathode, a water splitting electrolyzer was able to reach 10 mA cm-2 at a cell voltage of 1.52 V with robust durability. Various characterization techniques indicated that the long term stability and the activity for overall water splitting are due to the porosity, the electrochemically active constituents, and synergistic effects. This work could be inspiring in the design of Earth abundant and highly efficient electrocatalysts for overall water splitting, especially for OER.
开发用于析氢反应（HER）和析氧反应（OER）以及整体水分解的高性能非贵金属电催化剂是非常理想的，但仍然是一个巨大的挑战。在此，我们报告了一种简便的方法来合成超薄、无定形、多孔、富含氧和缺陷的 NiCoFe 磷酸盐纳米片（NSs）。由于其在 2D 方向上的微孔限制，可以减少电化学过程中的离子传输阻力，以及具有更高电化学活性表面积的缺陷富结构，这些负载在泡沫镍上的 NiCoFe 磷酸盐多孔纳米片（NiCoFe 磷酸盐 NSs/NF）有利于气态产物（H2 和 O2）的扩散，并在碱性电解质（1.0 M KOH）中表现出显著的 HER、OER 和整体水分解的催化性能和出色的稳定性。对于 OER 电催化剂，2D NiCoFe 磷酸盐 NSs/NF 在催化剂表面被氧化为 NiCoFe 氧化物/氢氧化物，表现出显著的 OER 活性，仅需 240 mV 的过电位即可达到 10 mA cm-2 的电流密度。对于 HER，2D NiCoFe 磷酸盐 NSs/NF 在仅需-231 mV 的低过电位下即可提供 10 mA cm-2 的电流密度。此外，采用 2D NiCoFe 磷酸盐 NSs/NF 作为阳极和阴极的电催化剂，水分解电解槽能够以 1.52 V 的电池电压达到 10 mA cm-2 的电流密度，具有强大的耐用性。各种表征技术表明，整体水分解的长期稳定性和活性归因于多孔性、电化学活性成分和协同效应。这项工作在设计用于整体水分解的丰富且高效的电催化剂方面具有启示性，特别是对于 OER。
