Researchers from the Council of Scientific and Industrial Research (CSIR) have developed a melamine-containing charge-assisted hydrogen-bonded organic system that has shown remarkable efficacy for electrocatalyzing water oxidation reaction (WOR). The research aims to establish the merits of charge-assisted organic systems as electrocatalysts for WOR, which could potentially supplant the necessity of transition-metal-based systems.
Outcomes:
- Melamine-based hydrogen-bonded systems show immense potential for multiple applications.
- BMA is a more efficient electrocatalyst for WOR compared to MA-120.
- BMA has minimal overpotential, low Tafel slope, high mass activity, TOF≈0.024 s−1, and excellent Faradaic efficiency ∼94.5 %.
- BMA has a precise molecular structure with strategically positioned nitrogen centers, a purpose-built electron-deficient surface, and robust stability.
- BMA is energy-efficient and scalable to synthesize from commonly available precursors.
Details:
Melamine and adipic acid-based hydrogen-bonded systems (ionic system BMA and co-crystal system MA-120) were synthesized hydrothermally under varying temperatures. X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were documented for both systems to gain insights into their surface chemical composition. The electrocatalytic performance of both systems was evaluated under alkaline and potentiodynamic conditions.
The research revealed that BMA delivered a significantly better WOR activity compared to MA-120, requiring an overpotential of 387 mV to reach a current density of 10 mA cm2, with a turnover frequency (TOF) of 0.024 s1. The mechanistic analysis of BMA revealed the advantages of a hydrophilic, preferably electron-deficient organocatalyst surface to augment the WOR efficiency.
The adsorption of reactants, interaction of the electrolyte with the catalyst, and the faster interfacial electron transfer aided by the electrostatic interactions were considered in the judicious designing of an efficient organo-electrocatalytic structure and purpose-modulated composition. The research sets a precedent in developing inexpensive, hydrogen-bonded organic materials with controlled structures that could find applications in sustainable energy in the future.
Melamine-Based Hydrogen-bonded Systems as Organoelectrocatalysts for Water Oxidation Reaction
Chhetri; Karthick; Karmakar; Kundu; Mitra
Full-text link: https://doi.org/10.1002/cssc.202300220
What this paper is about
- In order to supplant the necessity of transition-metal-based systems, carbon materials, organic molecules and hydrogenbonded systems are gaining attention and show immense potential for multiple applications.
- We aim to further establish the merits of charge-assisted organic systems as electrocatalysts for water oxidation using melamine-based hydrogen-bonded systems.
- Our experiments disclose that BMA delivered a significantly better electrocatalytic WOR activity compared to MA-120, requiring an overpotential of 387 mV to reach a current density of 10 mA cm, with a turnover frequency of 0.024 s. The activity of BMA was comparable to reported organo-electrocatalysts.
What you can learn
- BMA required a higher temperature of 160C, which resulted in a proton transfer from adipic acid to melamine ring nitrogen atom, resulting in a singly protonated melaminium moiety.
- PXRD pattern of both BMA and MA-120 affirmed their crystalline nature and their distinct differences from their precursors.
- Hence, the electrocatalytic proficiency of both materials was evaluated under alkaline conditions.
- XPS was recorded to elucidate the compositional changes on the surface of BMA@rec.
- Additionally, a high rate of mass transfer was observed in BMA, courtesy of an interconnected lamellar structure assisted by adipic acid-adipate-melaminium hydrogen bonding.
- The proficiency of BMA including minimal overpotential, low Tafel slope, high mass activity, TOF 0.024 s 1 and excellent Faradaic efficiency~94.5 % are comparable or superior to reported organoelectrocatalysts.
Core Q&A related to this research
What is the aim of the study?
Answer: The aim of the study is to establish the potential of melamine-based hydrogen-bonded systems as charge-assisted organic electrocatalysts for water oxidation reaction.
What are the results of the experiments conducted?
Answer: The experiments disclosed that the melamine-based hydrogen-bonded system BMA showed significantly better electrocatalytic activity for water oxidation reaction compared to its co-crystal counterpart MA-120. BMA required a higher temperature of 160C and had a turnover frequency of 0.024 s1, comparable to reported organo-electrocatalysts.
What is the composition of the melamine-based hydrogen-bonded systems BMA and MA-120?
Answer: BMA and MA-120 are composed of melamine and adipic acid-based hydrogen-bonded systems. BMA is an ionic system with a singly protonated melaminium moiety, while MA-120 is a co-crystal system.
What analytical techniques were used to investigate the chemical composition of BMA and MA-120?
Answer: X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) were used to investigate the surface chemical composition of both systems.
What is the advantage of using BMA as an electrocatalyst for water oxidation reaction?
Answer: BMA has a hydrophilic and electron-deficient organocatalyst surface that promotes interactions with the negatively charged electrolyte and the intermediates produced during WOR, facilitating interfacial electron transfer. Additionally, BMA has a high rate of mass transfer due to its interconnected lamellar structure assisted by adipic acid-adipate-melaminium hydrogen bonding. The proficiency of BMA including minimal overpotential, low Tafel slope, high mass activity, and excellent Faradaic efficiency makes it comparable or superior to reported organoelectrocatalysts.
Basic Q&A related to this research
What is melamine?
Answer: Melamine is a chemical compound with the formula C3H6N6. It is a white crystalline powder that is commonly used in the manufacturing of plastics, laminates, and flame retardants.
What are hydrogen-bonded systems?
Answer: Hydrogen-bonded systems refer to materials or structures that are held together by hydrogen bonds, which are strong electrostatic interactions between a hydrogen atom and a highly electronegative atom, such as nitrogen, oxygen, or fluorine.
What are electrocatalysts?
Answer: Electrocatalysts are materials that facilitate the conversion of electrical energy into chemical energy, or vice versa, by lowering the activation energy of a reaction. They are commonly used in applications such as fuel cells, electrolysis, and batteries.
What is the water oxidation reaction?
Answer: The water oxidation reaction (WOR) is a chemical reaction that involves the conversion of water molecules into oxygen gas and protons (H+), typically catalyzed by a material or system that can absorb light energy, such as a photosystem.
What are carbon materials and organic molecules?
Answer: Carbon materials refer to any substance that is made up primarily of carbon atoms, such as graphite, diamond, and carbon nanotubes. Organic molecules, on the other hand, are any molecule that contains carbon atoms bonded to hydrogen and/or other atoms, such as oxygen, nitrogen, and sulfur.
What are charge-assisted organic systems?
Answer: Charge-assisted organic systems refer to materials or structures that contain charged or polarized functional groups that can interact with other charged or polarized species, such as ions or solvent molecules, to enhance their chemical or physical properties.
What is BMA and MA-120?
Answer: BMA and MA-120 are two different melamine-based hydrogen-bonded systems that were synthesized and evaluated for their electrocatalytic activity in the water oxidation reaction.
What is proton transfer and adipic acid?
Answer: Proton transfer refers to the transfer of a hydrogen ion (H+) from one molecule to another, typically in the presence of a solvent or electrolyte. Adipic acid is a dicarboxylic acid that contains two carboxylic acid groups (-COOH) and is commonly used in the synthesis of polymers, such as nylon.
What are nitrogen centers and electron-deficient surface?
Answer: Nitrogen centers refer to the nitrogen atoms in a molecule or structure that can interact with other atoms or molecules through hydrogen bonding or other electrostatic interactions. An electron-deficient surface refers to a surface or material that has a relative lack of electrons or negative charge, which can enhance its interaction with positively charged or polarized species.
What are electrostatic interactions and water-mediated hydrogen bonding?
Answer: Electrostatic interactions are strong interactions between charged or polarized species, such as ions or dipoles, that can influence the properties and behavior of a material or system. Water-mediated hydrogen bonding refers to the interactions between water molecules and other species that are mediated by hydrogen bonds.
What is mass transfer and lamellar structure?
Answer: Mass transfer refers to the movement or diffusion of molecules or ions within a material or system. A lamellar structure refers to a layered or stacked arrangement of molecules or structures that can enhance the transport and interaction of molecules or ions within the material.
What is Faradaic efficiency?
Answer: Faradaic efficiency is a measure of the efficiency of an electrochemical process or reaction, typically expressed as the ratio of the number of electrons transferred in the reaction to the number of electrons supplied by the external circuit.
