IIT Guwahati Researcher’s Study finds new catalyst for efficient water splitting

A new study published in ACS Applied Materials & Interfaces by Moi, Sahu, and Qureshi has found a promising new catalyst for efficient overall water splitting. The researchers used doping with high-valent Mo and W metal centers to improve the performance of multimetallic FeVO(OH)/Ni(OH)2 systems.

Bullet Point Summary:

• High-valent Mo and W metal centers improve overall water-splitting efficiency.
• Two-step hydrothermal synthesis creates optimal catalyst
• Low overpotential and good performance in alkaline medium

The team used a two-step hydrothermal synthesis to create the catalyst to deposit Ni0.86Mo0.07W0.072 onto a commercial carbon paper substrate. The carbon paper offers better electrical conductivity and faster electron transport between the electrode and the active sites.

The resulting catalyst exhibited a low overpotential of 231 mV for OER and 156 mV for HER at a current density of 20 mA/cm2 in an alkaline medium. Additionally, the researchers found that introducing individual W6+ and Mo6+ improved the reaction rate and kinetics for water oxidation, leading to improved water-splitting efficiency.

The team also performed X-ray photoelectron spectroscopy (XPS) and found no inherent structural change before and after the stability test, indicating the catalyst’s durability. This experimental result validates that the codoping of high-valent Mo6+ and W6+ improves the reaction rate and kinetics for water oxidation.

This study’s results suggest that the catalyst developed by Moi, Sahu, and Qureshi has great potential for efficient overall water splitting and could be a step toward sustainable hydrogen production.

Tapping the Potential of High-Valent Mo and W Metal Centers for Dynamic Electronic Structures in Multimetallic FeVO(OH)/Ni(OH) 2 for Ultrastable and Efficient Overall Water Splitting

Moi; Sahu; Qureshi

Full text link: https://doi.org/10.1021/acsami.2c21041

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About the Research Paper

• Doping causes a reduction in the water dissociation energy and optimizes the adsorption energy for the reaction intermediates during the HER and OER processes.
• The d 0 transition metals with high oxidation states can accommodate incoming electrons to generate optimal bond length for reaction intermediates, accelerating water splitting.
• Ni 0.86 Mo 0.07 W 0.07 2 onto a commercial carbon paper substrate via a two-step hydrothermal synthesis, in which CP offers better electrical conductivity and faster electron transport between the electrode and the active sites.

Research Work

• As shown in, the introduction of individual W 6+ and Mo 6+ shifts, the Ni 2p peak toward higher BEs by 0.4 and 0.7 eV for NiW and NiMo, respectively, which symbolize a strong electronic interaction between W 6.
• FeVO with a reaction temperature of 150C yields the best HER and OER performance with an optimized reaction time of 4 h and NiMoW, signifying better reaction kinetics, as shown in. This experimental result validates that the codoping of high-valent Mo 6+ and W 6+ improves the reaction rate and kinetics for water oxidation.
• The Nyquist analysis is also performed at 0.16 V for HER to understand the charge-transfer kinetics of the reaction better, as shown in.
• XPS shows no inherent structural change before and after the stability test, indicating the catalyst’s durability.
• The as-synthesized electrocatalyst exhibits a low overpotential of 231 mV for OER and 156 mV for HER at a current density of 20 mA/cm 2 with small Tafel slope values of 24 mV/dec for OER and 67 mV/dec for HER, respectively, in an alkaline medium.
• NiMoW for OER and HER in 0.5 M H 2 SO 4 electrolyte solution and polarization curves normalized to ECSA for OER and HER, respectively; FESEM images and HRTEM image of FeVO.

Q: What is the purpose of doping in the study?

A: Doping causes a reduction in the water dissociation energy and optimizes the adsorption energy for the reaction intermediates during the HER and OER processes.

Q: What are the advantages of using a commercial carbon paper substrate in catalyst synthesis?

A: The commercial carbon paper substrate offers better electrical conductivity and faster electron transport between the electrode and the active sites.

Q: What is the effect of introducing individual W6+ and Mo6+ on the catalyst?

A: The introduction of individual W6+ and Mo6+ shifts the Ni 2p peak toward higher BEs by 0.4 and 0.7 eV for NiW and NiMo, respectively, which symbolizes a strong electronic interaction between W6+.

Q: What are the study’s best reaction temperatures and times for the FeVO catalyst?

A: A reaction temperature of 150C and a reaction time of 4 hours yields the best HER and OER performance for the FeVO catalyst, as shown in the study.

Q: How does using high-valent Mo6+ and W6+ affect the durability of the catalyst?

A: XPS analysis shows no inherent structural change before and after the stability test, indicating that the codoping of high-valent Mo6+ and W6+ does not negatively affect the durability of the catalyst.

(Push-pull chemistry) Just out in ACS AMI @IITGuwahati @serbonline @angew_chem https://t.co/WyzGBucgrg pic.twitter.com/ZisiFvXC07

— Materials Science Laboratory (@mq_iitg) January 18, 2023