Nitrogen-Enriched Carbon Nanobubbles and Nanospheres for Applications in Energy Harvesting, Storage, and CO₂ Sequestration

Multifunctional carbon nanomaterials have attracted remarkable consideration for use in various energy conversion and storage devices because of their ultrahigh specific surface area, unique morphology, and excellent electrochemical properties. Herein, we report the synthesis of highly uniform and ordered nitrogen-enriched carbon nanospheres (CS) and nanobubbles (CNB) by a modified Stöber reaction using resorcinol and formaldehyde in the presence of ethylenediamine as a nitrogen source. A comparative study of the prepared CS and CNB nanomaterials is presented here with potential use in a wide variety of applications involving large surface area and electrical conductivity. As counter electrode materials in solar cells, CNB and CS showed enhanced photoelectrochemical activity for catalytically reducing I3– to I– and improved capacitive behavior with a low charge transfer resistance and remarkable power conversion efficiency (PCE) of 10.40% with improved Jsc (20.20 mA/cm2) and Voc (0.73 V). The enhanced performance of the fabricated photoelectrochemical cell is due to the excellent point contact and good conductivity that offered better charge transportation of electrons with minimum recombination. The enhanced adsorption upon increasing the pressure without an apparent saturation level signified the large CO2 adsorption with 2 mmol/g for the CS. Additionally, the rectangular-shaped CV curve indicated the double-layer capacitive behavior, good electrochemical reversibility, and high-power characteristics, prerequisites for supercapacitor application. This study probes the practical possibility of nitrogen-enriched carbon nanostructures as a multifunctional material for prospective applications.