Key Takeaways & Executive Findings
- •• Carbon-based metal-free catalysts (CMFCs) offer a cost-effective and stable alternative to noble metal catalysts for electrosynthesis, addressing key limitations in scalability and sustainability. • The review systematically covers design strategies and catalytic mechanisms of CMFCs, highlighting their tunable structures and compositions for enhanced performance. • CMFCs are effective in synthesizing small-molecule chemicals such as hydrogen peroxide, ammonia, and chlorine, as well as various carbon- and nitrogen-based compounds. • Despite progress, challenges remain in improving selectivity and activity; future prospects include advanced material engineering and mechanistic understanding.
Abstract
Electrocatalysis is a key component of many clean energy technologies that has the potential to store renewable electricity in chemical form. Currently, noble metal-based catalysts are most widely used for improving the conversion efficiency of reactants during the electrocatalytic process. However, drawbacks such as high cost and poor stability seriously hinder their large-scale use in this process and in sustainable energy devices. Carbon-based metal-free catalysts (CMFCs) have received growing attention due to their enormous potential for improving the catalytic performance. This review gives a concise comprehensive overview of recent developments in CMFCs for electrosynthesis. First, the fundamental catalytic mechanisms and design strategies of CMFCs are presented and discussed. Then, a brief overview of various electrosynthesis processes, including the synthesis of hydrogen peroxide, ammonia, chlorine, as well as various carbon- and nitrogen-based compounds is given. Finally, current challenges and prospects for CMFCs are highlighted.
1. Introduction
Chemical manufacturing heavily relies on fossil fuels for its energy needs, which constitutes a significant portion of the world's energy demand[1]. Given the escalating energy crisis and environmental concerns, there is an urgent need to develop clean, low-cost and efficient renewable energy technologies to replace the traditional chemical manufacturing processes. Electrosynthesis emerges as a promising green strategy, utilizing clean electricity to drive electrochemical reactions for chemical synthesis. Unlike conventional industrial synthesis methods with high energy consumption, electrosynthesis technologies effectively reduce the energy barriers of electrochemical reactions, thus enabling the synthesis of valuable chemicals under milder conditions.
As a result, the direct electrochemical transformation of abundant raw ingredients, such as H2O, CO2, O2 and N2, into high-value-added chemicals and fuels has attracted increasing attention[2]. In these systems, electrocatalysts play a pivotal role in increasing reaction efficiency and regulating product selectivity[3–5]. This inherent capability makes catalysts indispensable in various electrochemical reactions, including the oxygen reduction/hydrogen oxidation reaction (ORR/HOR) in fuel cells[6–9], hydrogen and oxygen evolution reaction (HER/OER) in photo-/electro-water splitting[10–14], carbon dioxide reduction reaction (CO2RR) in the artificial carbon cycle[15–16], nitrogen reduction reaction (NRR) in artificial nitrogen fixation[17–19], and other electrosynthesis processes for generating high-value-added chemicals[20–22].
Currently, noble metal-based catalysts are commonly employed to enhance the conversion efficiency of reactants to products during the electrocatalytic process. However, the drawbacks such as high cost and poor stability seriously hinder their large-scale applications in electrosynthesis and sustainable energy devices[23–25]. Therefore, it is highly desirable to develop cost-effective electrocatalysts for overcoming these challenges and advancing the progress of electrochemical technologies.
Loading authentic research manuscript (Pages 1–5)...
SHI Lei, LI Yan-zhe, YIN Hua-jie, ZHAO Shen-long (2024). Carbon-based metal-free nanomaterials for the electrosynthesis of small-molecule chemicals: A review. New Carbon Materials. https://doi.org/10.1016/S1872-5805_N
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What are carbon-based metal-free catalysts (CMFCs) and why are they important?
CMFCs are carbon nanomaterials without metal active sites, offering advantages like low cost, high stability, and tunable properties. They are important as alternatives to noble metal catalysts in electrocatalysis, enabling sustainable and efficient chemical synthesis.
What small-molecule chemicals can be synthesized using CMFCs?
CMFCs can be used to synthesize hydrogen peroxide, ammonia, chlorine, and various carbon- and nitrogen-based compounds through electrochemical reactions.
What are the main challenges facing CMFCs in electrosynthesis?
Challenges include achieving high selectivity and activity comparable to metal-based catalysts, understanding reaction mechanisms, and scaling up production for industrial applications.
How do CMFCs contribute to sustainable energy technologies?
CMFCs enable the storage of renewable electricity in chemical form via electrosynthesis, reducing reliance on fossil fuels and lowering environmental impact.
What design strategies are used to enhance CMFC performance?
Strategies include element doping, chemical functionalization, and structural engineering (0D to 3D) to optimize catalytic activity and stability.
Related Technical Papers & Translations
Design and optimization of a high-efficiency distillation process for cellulosic fuel ethanol integrated with thermal coupling and molecular sieve adsorption
To address the challenges of high energy consumption and prominent costs in the traditional three-columns distillation process for cellulosic fuel ethanol, a distillation—molecular sieve coupling separation process is proposed. This process integrates a three-column (crude distillation column, first distillation column, second distillation column) system with a 3A molecular sieve adsorption deep dehydration unit. A thermal coupling network is constructed via differential pressure design (steam from medium/high-pressure columns as mutual heat sources, reboiler liquid waste heat for feed preheating), and molecular sieve adsorption conditions are optimized. The study first performs a thermodynamic consistency test on the ethanol—water system, determines optimal non-random two-liquid (NRTL) model binary interaction parameters via experimental data regression for Aspen Plus simulation. Aiming at minimum total annual cost (TAC), Aspen Plus is used to optimize process parameters (theoretical tray number, feed location, reflux ratio, side-draw position, etc.). Economic analysis shows this process reduces CO2 emission costs by 27.56%, TAC by 15.58% (to 5.123 × 106 USD·a-1), and increases ethanol purity to ＞99.6%, providing an effective solution for green, efficient separation.
A cohesion loss model for determining residual strength of deep bedded sandstone
Rock residual strength, as an important input parameter, plays an indispensable role in proposing the reasonable and scientific scheme about stope design, underground tunnel excavation and stability evaluation of deep chambers. Therefore, previous residual strength models of rocks established were reviewed. And corresponding related problems were stated. Subsequently, starting from the effects of bedding and whole life-cycle evolution process, series of triaxial mechanical tests of deep bedded s
Federated model with contrastive learning and adaptive control variates for human activity recognition
Recent attention to privacy issues demands a communication-safe method for training human activity recognition (HAR) models on client activity data. Federated learning (FL) has become a compelling technique to facilitate model training between the server and clients while preserving data privacy. However, classical FL methods often assume independent and identically distributed (IID) data among clients. This assumption does not hold true in practical scenarios. Human activity in real-world scena