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Ultrastable Catalysts for Water Splitting

Technology #16036n

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Researchers
Prof. Loh Kian Ping
Dr. Chen Zhongxin
Dr. Leng Kai
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Dr Tan Yan Ny
Manager (65)66012812
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Tech Offer 16036N Ultrastable Catalysts [PDF]

Ultrastable Catalysts for Water Splitting

Prof. Loh Kian Ping, Dr. Chen Zhongxin, Dr. Leng Kai

Department of Chemistry

NUS Graduate School for Integrative Sciences and Engineering

Industry Problem

Hydrogen energy is an ideal, clean and highly efficient secondary energy resource to replace petroleum fuels in the future energy production. As an alternative to the traditional platinum catalysts, transition metal dichalcogenides (TMDCs) have recently attracted attention because of their low-cost, global availability and acidic stability. To date, a lot of TMDC composites have been prepared and employed as the active electrode materials for hydrogen production. The exfoliation of TMDC nanosheets and functionalization with metal nanoparticles or conducting polymers have dramatically improved their activity towards hydrogen evolution. Unfortunately, they often exhibit inferior stability due to the loss of electrochemical active area during long-term operation process, such as the re-stack of TMDC nanosheets or the aggregation/dissolution of metal nanoparticles. Also, the complicated exfoliation and washing process of TMDC nanosheets limit their bulk production.

Solution

Prof Loh Kian Ping’s group from the Department of Chemistry has developed an ultrastable hydrogen evolution catalyst based on zero valent metal TMDC composites. Due to the unique physical structure of the catalyst, superior hydrogen evolution activity and stability is demonstrated compared to the exfoliated TMDC nanosheets and benchmark Pt/C catalyst. For example, MoS2 catalysts with ~ 10 wt% platinum loading exhibits stable hydrogen evolution activity for 120,000s (~ 33.3 hours) at a current density up to 50 mA/cm2 (Fig. 1(a)). On the other hand, the benchmark 40% Pt/C catalyst shows increasing losses (increasing overpotential) through the measurement period (Fig. (1(a)). In addition, the 10% Pt/MoS2 catalysts show comparable hydrogen evolution activity compared to the benchmark 40 wt% Pt/C catalyst, with an overpotential down to 20 mV (Fig. 1(b)) and a Tafel slope of ~20 mV/dec (Fig. 1(c)). Hence, lower Pt loading is demonstrated in our TMD catalyst, leading to potential cost saving. This is among the best performance reported to date for TMD. A 25 cm2 membrane-electrode assemblies can be made by coating onto carbon papers/cloths (Fig. 2(a) & (b)) and subsequent hot-pressing with Nafion® membrane (Fig. 2(c)), thus showing the scalability of our processing methods. NUS has filed for patent protection for this invention.


Fig. 1: Hydrogen evolution performance of zero valent metal MoS2 catalysts: (a) long-term stability test at 50 mA/cm2(b) Linear Sweep Voltametry curves and corresponding (c) Tafel plots;, and (d) cycling performance of Pt-MoS2 catalysts (Inset: TEM image after 10,000 cycles). All experiments were conducted in 0.5 M H2SO4 at 70 μg/cm2 loading.at room temperature.


Fig. 2: Digital photos of a 25 cm2 membrane-electrode assemblies using zero valent metal MoS2 catalysts: (a) coating onto carbon paper, (b) coating onto carbon cloth, (c) combined with Nafion® membrane and commercial 40% Pt/C gas diffusion electrode, all at a loading of 1 mg/cm2.

Keywords: Water splitting, catalyst, Hydrogen, evolution, transition metal dichalcogenide, stable

Value Proposition

•  Ultra-stable hydrogen evolution catalyst in water-splitting for long term operation.

•   Unique physical structure enables up to 4X lower Pt metal loading compared to benchmark Pt/C catalyst to achieve comparable hydrogen evolution performance

  => potentially cost saving.

•  Demonstrated scalability through fabrication of membrane-electrode assemblies using zero valent metal MoS2 catalysts.

Potential Application

•  Clean energy application

•  Catalyst for water splitting

For more information, contact:

NUS Industry Liaison Office

Case Manager: Tan Yan Ny

+65 6516 7175/ +65 66012812

iloquery@nus.edu.sg/ tan.yan.ny@nus.edu.sg

Principal Investigator: Prof Loh Kian Ping

chmlohkp@nus.edu.sg

Acknowledgement

This research is supported by  the Ministry of Defence, Singapore under the “Defence Innovative Research Programme“, Project Agreement No. 9013103795Ref : ID14274N