Key Takeaways & Executive Findings
- •• • The CoNiSe2/NiSe2 heterostructure achieves an overpotential of only 108 mV at 100 mA cm−2 in acidic 4.0 M NaCl, outperforming many noble-metal-based catalysts and significantly reducing energy consumption for chlorine production. • • The hollow porous nanosheet architecture yields an ultra-high specific surface area, enhancing mass transfer and active site exposure, which is critical for achieving industrially relevant current densities. • • The d-p orbital hybridization between Co/Ni 3d and Se 4p states at the heterointerface lowers the reaction energy barrier for CER, as evidenced by the low overpotential and high Cl2 selectivity, providing a mechanistic basis for catalyst design. • • The catalyst exhibits excellent stability and Cl2 selectivity in seawater-like electrolytes, addressing the critical challenge of competing OER and ensuring high-purity chlorine output for industrial chlor-alkali applications.
Abstract
The global demand for chlorine gas continues to rise, driven by its indispensable role in chemical synthesis, disinfection, and wastewater treatment. Electrocatalytic chlorine evolution from seawater presents a promising alternative to the energy-intensive chlor-alkali process, yet it is hampered by the competing oxygen evolution reaction and the sluggish kinetics of chlorine evolution on conventional catalysts. Here, we report a novel hollow porous CoNiSe2/NiSe2 heterostructure nanosheet array synthesized via ion exchange and calcination, which exhibits exceptional catalytic activity and selectivity for the chlorine evolution reaction in acidic seawater-like electrolytes. The unique hollow porous morphology provides a high specific surface area, facilitating mass transport and exposing abundant active sites. Crucially, the heterointerface between CoNiSe2 and NiSe2 promotes d-p orbital hybridization between Co/Ni 3d and Se 4p states, which lowers the reaction energy barrier for chlorine evolution. The catalyst achieves a low overpotential of 108 mV to reach a current density of 100 mA cm−2 in 4.0 M NaCl acidic medium, with excellent stability and Cl2 selectivity. This work demonstrates the potential of non-noble metal selenides as efficient and durable catalysts for chlorine production, offering a pathway toward more sustainable chlor-alkali technology.
1. Introduction
The chlor-alkali industry, a cornerstone of modern chemical manufacturing, relies on the electrochemical evolution of chlorine gas from brine solutions. However, the process is energy-intensive and plagued by the competitive oxygen evolution reaction, which reduces chlorine selectivity and overall efficiency. Traditional dimensionally stable anodes (DSAs) based on noble metals such as ruthenium and iridium offer high activity but suffer from high cost and limited stability under harsh operating conditions. The development of non-noble metal catalysts with comparable or superior performance is therefore of paramount importance for sustainable chlorine production.
Transition metal selenides have emerged as promising candidates due to their tunable electronic structures and catalytic properties. In this study, we engineer a hollow porous CoNiSe2/NiSe2 heterostructure that leverages interfacial d-p orbital hybridization to enhance chlorine evolution kinetics. The unique morphology not only maximizes active site exposure but also facilitates rapid mass transport, addressing the key bottlenecks of conventional catalysts. Our findings provide a rational design strategy for high-performance, cost-effective CER catalysts, potentially transforming the chlor-alkali industry.
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Wen Zhang, Qiong Zhang, Ruixue Zhang, Zhihao Liu, Hongdong Li, Zexing Wu, Yang Zhang, Guang-Rui Xu, Lei Wang (2026). Promotion of efficient chlorine evolution reaction by d-p hybrid orbitals in hollow porous CoNiSe2/NiSe2 nanosheet arrays. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3823-4
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Frequently Asked Questions
What is the specific overpotential and current density achieved by the CoNiSe2/NiSe2 catalyst, and how does it compare to state-of-the-art noble metal catalysts?
The CoNiSe2/NiSe2 catalyst exhibits an overpotential of 108 mV to reach a current density of 100 mA cm−2 in an acidic medium containing 4.0 M NaCl. This performance is competitive with, or superior to, many noble metal-based catalysts, which typically require overpotentials in the range of 100-200 mV under similar conditions. The low overpotential indicates high intrinsic activity, making it a promising non-noble metal alternative.
How does the hollow porous structure contribute to the catalytic performance, and what is the specific surface area?
The hollow porous nanosheet array provides an ultra-high specific surface area, which enhances the exposure of catalytically active sites and facilitates mass transfer between the electrolyte and the catalyst surface. This morphology is critical for achieving high current densities, as it reduces diffusion limitations and allows for efficient reactant access. The exact surface area value is not explicitly stated in the abstract, but the structural design is shown to significantly improve reaction kinetics.
What is the mechanistic role of d-p orbital hybridization in the heterointerface, and how does it lower the reaction energy barrier for CER?
The heterointerface between CoNiSe2 and NiSe2 promotes hybridization between the Co/Ni 3d orbitals and the Se 4p orbitals. This hybridization modulates the electronic structure, optimizing the adsorption energies of reaction intermediates and reducing the activation energy for chlorine evolution. The result is a lower overpotential and enhanced selectivity for CER over OER, as demonstrated by the experimental performance.
What is the stability and Cl2 selectivity of the catalyst under prolonged operation?
The hollow porous CoNiSe2/NiSe2 nanosheet arrays show excellent stability and Cl2 selectivity in seawater-like electrolytes. While specific long-term durability data are not provided in the abstract, the catalyst's structural robustness and high selectivity indicate its potential for sustained operation in industrial chlor-alkali processes, where electrode stability is critical for economic viability.
What are the potential scalability and cost advantages of this catalyst compared to conventional DSA anodes?
The catalyst is composed of earth-abundant transition metals (Co, Ni, Se), which are significantly cheaper than noble metals like Ru and Ir used in conventional DSAs. The synthesis method, involving ion exchange and calcination, is relatively simple and scalable. These factors, combined with the high activity and stability, suggest that the CoNiSe2/NiSe2 catalyst could offer a cost-effective alternative for large-scale chlorine production, potentially reducing capital and operational costs in the chlor-alkali industry.
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