Key Takeaways & Executive Findings
- •• A novel micellar co-polymerization strategy enables the synthesis of P, N co-doped hollow carbon nanospheres with a unique pore structure and defect-rich framework. • The combined effect of graphitic nitrogen and phosphorus-carbon bonds modulates the local electronic structure of adjacent carbon atoms, facilitating electron transfer for enhanced HER. • The optimized HCN catalyst carbonized at 1100 °C exhibits superior HER activity and outstanding stability (70 h at 10 mA cm−2) in alkaline water. • This work provides a promising metal-free catalyst design for efficient and durable hydrogen production via alkaline water electrolysis.
Abstract
The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction (HER) is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water. Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity. Nevertheless, both the structural characteristics and the underlying mechanism are not well understood, especially for doping with two different atoms, thus limiting the use of these catalysts. We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres (HCNs) by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface, followed by doping with phytic acid and carbonization. The unique pore structure and defect-rich framework of the HCNs expose numerous active sites. Crucially, the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer. As a result, the HCN carbonized at 1100 °C exhibited superior HER activity and an outstanding stability (70 h at a current density of 10 mA cm−2) in alkaline water, because of the large number of graphitic nitrogen and phosphorus-carbon bonds.
1. Introduction
The enormous consumption of fossil fuels has resulted in serious environmental issues and energy challenges, forcing us to explore clean secondary energy sources, such as clean hydrogen with high specific energy density[1–2]. Hydrogen production through alkaline electrolysis powered by renewable energy has been regarded as one of the most promising approaches[3–4]. However, the high cost and low reserve of noble metal catalysts (e.g., Pt and Ir) limit their widespread applications[5]. As for various transition metals (e.g., Co, Ni, Fe, Mo) and their derivatives, potential corrosion and dissolution sensitivity issues hinder the long-term service of catalysts[6–7]. In contrast, metal-free carbon-based catalysts exhibit unique merits, including low cost, adjustable porous nanostructure, tunable functionalities, and well acid/alkali resistance, which could function effectively in catalyzing hydrogen evolution reaction (HER)[8]. On the one hand, constructing a well-defined porous nanostructure could expand the active surface area and expedite mass/charge transfer[9–10]. Moreover, anchoring carbon functionalities by heteroatom doping has been demonstrated as an effective approach to modulate electronic structures and improve electrochemical properties[11–18]. The mono-heteroatom doping has been extensively studied previously, which is due to the electronegativity difference between C atom and doped heteroatom, the doping redistributes the charge and spin densities of the C atoms, facilitating the charge transfer at the active sites. However, there is still plenty of scope for further optimizing the HER performances[19]. In this context, the dual-heteroatom co-doping strategy triggers the combined effect in modulating the local electronic structure and promoting HER. The electronegativity difference between the dual-heteroatom and C triggers a combined coupling effect, which is able to modulate the unique electron-donor properties of the carbon matrix and effectively activate the neighboring carbon atoms, thereby significantly enhances the HER activity and accelerates the HER process[20–21]. Consequently, it is imperative to devise dual-heteroatom co-doped carbon catalysts for enhancing the HER activity from both scientific and technological viewpoints.
Previous reports indicate that dual-heteroatom doping featuring reverse electronegativity could generate the combined coupling effect to modulate the local electronic structure of the carbon matrix and facilitate the charge transfer process, suc
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HAN Yi-meng, XIONG Hao, YANG Jia-ying, WANG Jian-gan, XU Fei (2025). P, N co-doped hollow carbon nanospheres prepared by micellar co-polymerization for increased hydrogen evolution in alkaline water. SinoTechIntel Verified Research. https://doi.org/10.1016/S1872-5805(NCM2025-40-01-11)
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Frequently Asked Questions
What is the main innovation of this research?
The research introduces a novel micellar co-polymerization method to synthesize phosphorus and nitrogen co-doped hollow carbon nanospheres, which exhibit enhanced hydrogen evolution reaction (HER) activity in alkaline water due to the combined effect of graphitic nitrogen and phosphorus-carbon bonds.
How were the P, N co-doped hollow carbon nanospheres prepared?
The nanospheres were prepared by copolymerizing pyrrole and aniline at a Triton X-100 micelle interface, followed by doping with phytic acid and carbonization at high temperatures (e.g., 1100 °C).
What is the significance of the dual heteroatom doping?
Dual doping with phosphorus and nitrogen creates a combined coupling effect that modulates the local electronic structure of adjacent carbon atoms, facilitating electron transfer and enhancing the catalytic activity for hydrogen evolution.
What are the key performance metrics of the optimized catalyst?
The HCN carbonized at 1100 °C exhibited superior HER activity and outstanding stability, maintaining a current density of 10 mA cm−2 for 70 hours in alkaline water.
Why are metal-free carbon-based catalysts important for hydrogen production?
Metal-free carbon-based catalysts offer advantages such as low cost, adjustable porous nanostructure, tunable functionalities, and excellent acid/alkali resistance, making them promising alternatives to noble metal catalysts for sustainable hydrogen production.
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