Electrochemical water splitting of 3D binder-free hydrothermally synthesized Co 3 O 4 /unidirectional carbon cloth.

The development of hydrogen energy sources based on electrochemical water splitting is of increasing interest due to its advantages in energy and environmental fields. In this study, Co 3 O 4  was decorated on carbon cloth (CC) by a hydrothermal method and was used as an electrode for water splitting. The structural and morphological properties of the materials are assessed using a range of reliable techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with EDX mapping, and diffuse reflectance spectroscopy (DRS). Results indicate that the Co 3 O 4 /CC material was synthesized at 140 °C for 9 h and calcined at 350 °C achieving a superior overall water-splitting activity in the direction of hydrogen evolution reaction (HER) reaction than that of the oxygen evolution reaction (OER). In detail, HER characteristics with an overpotential at -0.234 V and a current density at 10 mA cm -2 . In addition, the Co 3 O 4 /CC material also gives overpotential at 0.54 V for OER process. Furthermore, the electrochemical surface area of Co 3 O 4 /CC material is 7.6 times higher than CC electrode. Moreover, the CC fabric is destroyed when the annealing temperature is higher than 350 °C, leading to a significant decrease in the activity of Co 3 O 4 /CC. The as-prepared Co 3 O 4 shows good adhesion and stability based on CC substrate without binder substance or further treatment of CC.