Source: School of Chemistry
Written by: School of Chemistry
Edited by: Wang Dongmei

With the increasing consumption of fossil fuels in recent years and the deterioration of environmental problems, the energy crisis is imminent, and the demand for new sustainable energy is also becoming more and more urgent. Electrocatalytic water splitting to produce the hydrogen energy is expected to lead the human out of this dilemma. However, since the most active electrodes for the electrocatalytic water splitting is confined to noble metals or noble metal oxides (e.g. Pt for hydrogen evolution and IrOxfor oxygen evolution), their high cost and rare reserve strictly hinder the large-scale application of this promising technology. How to use other low-cost materials with an effective performance is becoming one of the hotspots in the field of energy conversion and storage.

Recently, Professor Hongbing Ji and Professor Yexiang Tong (Co-corresponding authors) from the School of Chemistry at Sun Yat-sen University have collaborated and published a paper entitled “Cost-Effective Alkaline Water Electrolysis Based on Nitrogen- and Phosphorus-Doped Self-Supportive Electrocatalysts” in Advanced Materials to tackle this issue, demonstrating that a low-cost stainless steel-derived material can be utilized to effectively split the water under basic solution. By modifying the flexible 304-stainless steel with acid etching and following annealing under ammonia and phosphine gas, the researchers obtained efficient anodes and cathodes for oxygen and hydrogen evolution, respectively, and their excellent performance is even comparable with the noble materials like Pt and IrOx. The superior electrodes exhibit an amount of merits as follows:

(1) Low-cost: The net price of flexible 304-stainless steel is 40$ per square meter, while other commonly used non-precious alternative metal materials have clearly higher price, such as nickel 100 US dollars per square meter and carbon cloth 875 US dollars per square meter. Obviously, the precious metals have much higher prices.

(2) Excellent performance: Due to the increase in active specific surface area originated from the etching and doped N/P element from the annealing under gases, the N, P-active electrode performances is comparable to Pt for the hydrogen evolution activity, and the N-active electrode is better than IrOxon oxygen evolution. The water splitting device assembled with the N and P active electrode notably outperformed that of the conventional Pt-IrOxsystem. It also possesses a narrower overpotential.

(3) Reliable stability: During the continuing 6 days running, the device had not exhibited any declination and attenuation, indicating its prominent potential on the practical application.

In this paper, the authors reported a method to prepare an efficient electrocatalyst on the water splitting by using 304 stainless steel mesh as raw material. Through the systemic investigation of the N/P dopant influencing the reaction activity in the material, an excellent device used for water splitting was assembled, and its performance is even compatible to the noble metal assembled devices. Because of its distinguished advantages on low cost and stability, the produced electrodes can be greatly promising on boosting the applications of the electrocatalytic water splitting.

Link to the paper: http://onlinelibrary.wiley.com/doi/10.1002/adma.201702095/full