Design of a High-Efficiency Bifunctional Electrocatalyst: Rich-Nitrogen-Doped Reduced Graphene Oxide-Modified Carbon Cloth-Growing Nickel–Iron Complex Oxides for Overall Water Splitting

Abstract

The rapid development of high-efficiency and lowprice bifunctional electrocatalysts for replacing precious metal catalysts has been confronted with an enormous challenge for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, a three-dimensional cubic electrocatalyst of nickel− iron complex oxides grown on the rich-nitrogen-doped reduced graphene oxide (NiFe 2 O 4 @N-rGO-CC) was synthesized through the two-step hydrothermal reaction. The experimental integrity test revealed that NiFe 2 O 4 @N-rGO-CC exhibited excellent electrocatalytic performance and long-term stability in both alkaline and acid electrolytes. In a 1.0 M potassium hydroxide (KOH) solution, lower overpotentials of 479 and 156 mV were acquired to deliver the current density of 10 mA•cm −2 for both OER and HER, respectively. Besides, NiFe 2 O 4 @N-rGO-CC also exhibited excellent HER performance in 0.5 M H 2 SO 4 solution, which provided a lower overpotential of 188 mV with a current density of 10 mA•cm −2 . NiFe 2 O 4 @N-rGO-CC showed extremely stable durability over a long time period of 30 h for OER and 50 h for HER in alkaline medium, and 40 h for HER in acid medium. Furthermore, NiFe 2 O 4 @N-rGO-CC required only 1.67 V to deliver the current density of 10 mA•cm −2 for alkaline water splitting, and it could be maintained for up to 70 h without any significant potential reduction. As evidenced, rich N-doped rGO modified the carbon cloth, which could significantly increase the electrocatalytic active sites for OER and HER. This work provided a novel approach for synthesizing transition bimetallic oxides grown on rich N-doped rGO-CC electrocatalysts as an innovative application of the lowcost substitution of precious metal electrocatalysts with highly efficient overall water splitting.

Electrochemical Oxygen Evolution Catalyzed by Zn0.76Co0.24S-Enriched ZnCo2S4/ZnCr2O4 Nanostructures

“…The development of sustainable clean energy and novel electrochemical energy storage devices has attracted significant scientific interest due to the rapidly growing global energy demand and public concerns about global warming, the greenhouse effect, and pollution from fossil fuels. , Given the limited supply of conventional resources such as petroleum derivatives and carbon-based fuel, tremendous efforts have been made to advance various innovative technologies to generate inexhaustible, environmentally friendly, and affordable energy sources. The technique of generating hydrogen and oxygen through water splitting, also known as electrocatalysis, optimally uses the numerous transition metal oxides (TMOs), transition metal sulfides, and their hybrid compounds as catalysts. − Among the various cutting-edge inventions, electrocatalysis is the most popular innovation over fossil fuels to meet current and future energy needs through increased environmental friendliness. − The hydrogen evolution process (HER) and oxygen evolution reaction (OER), two elementary reactions, have proven to be the simplest and least expensive methods to produce oxygen and hydrogen. − Therefore, effective electrocatalysts with low overpotentials are typically considered vital in accelerating this process to increase the reaction rate and reduce energy consumption. − Because of the advanced kinetics and lower overpotentials, OER prefers an alkaline medium to an acidic one at room temperature …”

Constructing Stable MoOx-NiSx Film via Electrodeposition and Hydrothermal Method for Water Splitting

“…There has been a significant advancement in carbon cloth (CC)-template-based electrocatalysts, which have been proven to have a high specific surface area and electrical conductivity for the HER [13][14][15][16]. For the past few years, efforts have been made to develop synthetic technology and modify materials [17][18][19][20][21][22], such as hydrothermal synthesis, calcine, solvothermal strategy, and phosphorization, in order to use CC-based HER catalysts that have low overpotential and long-term durability [23][24][25][26][27]. Using a hydrothermal reaction and nitridation method, Yao et al synthesized Cr-doped Co 4 N nanorod arrays on CC (Cr-Co 4 N/CC), which had high efficiency for the HER in alkaline media [28].…”