Two-Dimensional Amorphous Cobalt Oxide Nanosheets/N-Doped Carbon Composites for Efficient Water Splitting in Alkaline Medium

Abstract

The development of earth-abundant, inexpensive, and durable noble-metal-free bifunctional electrocatalysts is important to design anion exchange membrane water electrolyzers (AEMWEs). In recent years, tremendous efforts have been carried out to prepare two-dimensional (2D) amorphous noblemetal-free catalysts for alkaline water splitting as they have unique characteristics in catalysis. In this report, a 2D amorphous cobalt oxide nanosheet/nitrogen-doped carbon composite (CoO x /CN x ) was prepared for water splitting in the base. The catalyst displays excellent oxygen evolution reaction (OER) activity with 310 mV overpotential at 10 mA/cm 2 current density and 60.7 mV/dec Tafel slope value. The CoO x /CN x also shows very good long-term OER stability in the base. The CoO x /CN x composite also shows moderate hydrogen evolution reaction (HER) activity, and the activity increases with increasing reaction time. We demonstrate that the HER activity increases with increasing HER cycle because of the surface modification of the catalyst. The CoO x /CN x also shows excellent overall water-splitting activity as well as durability. The catalyst possesses high catalytic activity because of its 2D, amorphous sheetlike morphology, strong synergistic interactions, porosity, large electrochemical surface area, and easy access to abundant active sites. Thus, this result may offer a prospect to design a noble metal-free electrocatalyst for AEMWEs and other renewable energy-based devices.

Hydrogen spillover enhances alkaline hydrogen electrocatalysis on interface-rich metallic Pt-supported MoO3

“…2,3 Hydrogen is a potential alternative to fossil fuels because of its high gravimetric energy density as well as its carbon-free H 2 O emissions. 4,5 Wind, tidal, and solar energy are several renewable alternatives to fossil fuels, but these are regional and seasonal. 6,7 Therefore, researchers have investigated several methods to store renewable energies and use them during energy crises.…”

Electrocatalytic Oxidation of Urea and Ethanol on Two-Dimensional Amorphous Nickel Oxide Encapsulated on N-Doped Carbon Nanosheets

“…This method can provide clean and efficient ultra-pure hydrogen . In the water electrolysis method, there are two sequential half-reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), which take place at the anode and cathode, respectively. − The HER is a two-electron process and can easily catalyze at low overpotentials . However, the OER is a four-electron process that is believed as a sluggish process, therefore, requires a large overpotential .…”

“…7−9 The HER is a two-electron process and can easily catalyze at low overpotentials. 10 However, the OER is a four-electron process that is believed as a sluggish process, therefore, requires a large overpotential. 11 Since the OER plays an important role in electrochemical water splitting, an alternative and highly effective anodic electrocatalyst that can boost the reaction is extremely urgent and necessary for hydrogen production.…”

Free-Standing Dendritic Nanostructured Co/CNT/Carbon Nanofiber Composites for Efficient Water Splitting in Alkaline Media

“…Consequently, the exploration of low-cost alternative catalysts for noble metals has drawn much more attention and it is still an imperative challenge . Metal sulfides, , oxides, phosphides, nitrides, carbides, , and metal alloys have been extensively studied in electrocatalysis. In particular, transition-metal catalysts with exposed defects, vacancies, and edges have proven to be prospective catalysts for HER and OER attributed to their superior features such as excellent catalytic stability and electrocatalytic properties. − There are two methods to stabilize the defects, vacancies, and edges of transition-metal catalysts in the synthesis process and enhance the electrical contact with the active sites.…”