Electrodeposition of Ni-Co-Fe mixed sulfide ultrathin nanosheets on Ni nanocones: low-cost, durable and high performance catalyst for electrochemical water splitting
The development of a bi-functional active and stable catalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an essential challenge in electrochemical overall water splitting. In this study, firstly, NNCs (NNCs) were formed using electrochemical deposition, and then Ni-Co-Fe based mixed sulfide ultrathin nanosheets were obtained by directly depositing on the surface of the nanocones using the CV method. With a hierarchical structure of Ni-Fe-Co-S nanosheets, not only high active surface area was created, but also the electron and mass transfer were enhanced. This structure also led to the faster release of hydrogen bubbles from the surface. A value of 106 mV overpotential was required on the surface of this electrode to generate a current of 10 mAcm-2 in the HER, whereas, for the OER, 207 mV overpotential was needed to generate a current density of 10 mAcm-2. Furthermore, this electrode required 1.54 V potential to generate a current of 10 mAcm-2 in the total electrochemical water splitting. The resulting electrode also exhibited reasonable electrocatalytic stability, and after 10 hours of electrolysis in the overall water splitting reaction, the voltage change was negligible. This study introduces a simple, efficient, reasonable and cost-effective method of creating an effective catalyst for overall water splitting process.