Bahra University

Mandi: A multi-Institutional team from IIT Mandi, IIT Delhi and Yogi Vemana University have replicated the structure of the leaf in a low-cost inorganic catalyst to enable light-induced production of green hydrogen and ammonia. 

A researcher’s team, led by Dr. Venkata Krishnan, Associate Professor, IIT Mandi, have addressed the main bottlenecks of photocatalysis – poor light absorption, photogenerated charge recombination and the need for catalytically active sites to use sunlight effectively to drive chemical reactions. 

The team has improved the properties of a low-cost photocatalyst, calcium titanate through an approach called ‘defect engineering’ and have shown its efficacy in producing green hydrogen and ammonia in two light-driven reactions. Specifically, the defect engineering was done by incorporation of oxygen vacancies in a controlled manner. These oxygen vacancies act as catalytically active sites to promote the surface reactions and thereby enhance photocatalytic performance. 

“We were inspired by the light-harvesting mechanism of leaves and replicated the surface and internal three-dimensional microstructures of the leaf of the Peepul tree in the calcium titanate to enhance the light-harvesting properties,” said the lead researcher. By this way, they improved the efficiency of light absorption. In addition, the introduction of defects in the form of oxygen vacancies helped to solve the problem of the recombination of photogenerated charges.

The scientists studied the structural and morphological stability of the defect engineered photocatalyst and showed that their photocatalyst showed excellent structural stability as the engineered oxygen vacancy defects were well-retained after recyclability studies. They used the catalyst to produce hydrogen from water and ammonia from nitrogen, using the sun’s rays as the activator at ambient temperatures and pressures.

Dr. Venkata Krishnan expects that their work would provide a direction for the smart design of defect-engineered three-dimensional photocatalysts for green energy and environment-oriented applications.