Cobalt Carbonate-Coated Nitrogen-Doped Carbon Nanotubes with a Sea-Cucumber Morphology for Electrocatalytic Water Splitting

Abstract

Herein, we report CoCO 3 -coated nitrogen-doped carbon nanotubes (NCNTs) with a sea cucumber-like morphology for water splitting. The sample with a CoCO 3 content of 26.8 wt % (CoCO 3 /NCNT-1) exhibits excellent performance for the hydrogen evolution reaction in 1.0 M KOH electrolyte with an overpotential of 58 mV to reach 10 mA cm −2 , better than the most nonnoble metal catalysts reported; meanwhile, it exhibits superior electrocatalytic activity for the oxygen evolution reaction. The excellent performance of the catalyst is attributed to the nanotip effect caused by the sea-cucumber-like morphology. Notably, CoCO 3 /NCNT-1 can attain turnover frequencies of 2.7 s −1 at an overpotential of 50 mV, higher than that of Pt/C (1.5 s −1 ). A cell constructed using CoCO 3 /NCNT-1 as the catalyst of the electrode pair needs a low cell voltage of 1.54 V at 10 mA cm −2 , superior to most reported cells. In addition, CoCO 3 /NCNT-1 can maintain 10 mA cm −2 for overall water splitting for 100 h without activity loss.

Heterogeneous Fe-Doped NiCoP–MoO3 Efficient Electrocatalysts for Overall Water Splitting

“…2−4 Among the many methods for producing hydrogen, electrolysis of water to produce hydrogen is the most promising. 5,6 Electrochemical water splitting generally consists of two parts, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). 7,8 Usually, water electrolysis requires a high overpotential and is an energyintensive process.…”

“…Hydrogen as environment-friendly energy does not produce any polluting gas after combustion, so the development of hydrogen energy is an important link to achieve sustainable development. − Among the many methods for producing hydrogen, electrolysis of water to produce hydrogen is the most promising. , Electrochemical water splitting generally consists of two parts, the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). , Usually, water electrolysis requires a high overpotential and is an energy-intensive process. Traditional precious metal materials such as Pt for HER , and RuO 2 for OER , are extremely expensive and scarce resources, making them completely unsuitable for large-scale commercial applications.…”

Layered Porous Graphitic Carbon Nitride Stabilized Effective Co2SnO4 Inverse Spinel as a Bifunctional Electrocatalyst for Overall Water Splitting

“…Ever-increasing environmental issues and global energy demands have evolved into serious hurdles in the 21st century, posing difficulties for sustainable energy systems around the world. In comparison to fossil fuels, the lightest gas hydrogen is termed an energy carrier and considered to be a zero-carbon-emission fuel, making it a clean and sustainable energy to meet the global needs for energy applications. − It is known that H 2 can be obtained from biomass, water, natural gas, and coal. So far, H 2 has been produced in the industrial scale by frozen coke oven gas, thermal cracking of petroleum, water gas, and reforming of natural gas processes, where a large amount of fossil fuels is required to produce H 2 along with the emission of CO 2 , leading to severe environmental issues. , Among the existing methodologies, the process of electrocatalytic overall water splitting is green, eco-friendly, and an eminent tool for ecological H 2 production.…”

Porous Ni3S2–Co9S8 Carbon Aerogels Derived from Carrageenan/NiCo-MOF Hydrogels as an Efficient Electrocatalyst for Oxygen Evolution in Rechargeable Zn–Air Batteries

“…The massive exploitation and rapid consumption of petroleum have caused continuous harm to the environment, such as the greenhouse effect, light pollution, water pollution, etc. There is no doubt that the continued use of traditional fossil fuels will aggravate these problems. − Due to their advantages of high theoretical energy density, green environment protection, high safety, and low cost, zinc–air batteries have attracted attention from many scientists in the fields of energy conversion and wearable batteries, and oxygen evolution reaction (OER) plays a crucial part in zinc–air batteries. − At present, the oxides of precious metals Ir and Ru are the most widespread catalysts, their lack of resources, high cost of use, and poor stability force researchers to continue to explore cheap, efficient, and stable OER catalysts. − Nevertheless, because the OER process is influenced by the complicated reaction process, the overpotential is extremely high. , Therefore, developing an efficient electrocatalyst is an important method to reduce the OER overpotential and promote the rapid reaction. − Transition metal sulfides (TMSs) are rich in resources with excellent performance, , and the synergistic effect of transition metal sulfides and the heteroatom-doped carbon material can improve the conductivity of sulfide, avoid the occurrence of aggregation phenomenon, and thus improve the electrochemical activity …”

“…7−10 Nevertheless, because the OER process is influenced by the complicated reaction process, the overpotential is extremely high. 11,12 Therefore, developing an efficient electrocatalyst is an important method to reduce the OER overpotential and promote the rapid reaction. 13−18 Transition metal sulfides (TMSs) are rich in resources with excellent performance, 19,20 and the synergistic effect of transition metal sulfides and the heteroatom-doped carbon material can improve the conductivity of sulfide, avoid the occurrence of aggregation phenomenon, and thus improve the electrochemical activity.…”