In a fast-moving industrial world where carbon emissions continue to rise, hydrogen has emerged as a cleaner and more sustainable alternative to fossil fuels. Its use as a green energy source plays an important role in mitigating the effects of climate change. Yet, the sustainable production of hydrogen remains a challenge, as most existing methods depend on costly metals such as platinum or unstable materials that degrade in water. Addressing these challenges, researchers at the Indian Institute of Technology Gandhinagar (IITGN) have developed a new lead-based halide perovskite material that is structurally stable in water and does not require any noble-metal co-catalyst.
The study, conducted in collaboration with scientists from Université de Picardie Jules Verne, France, demonstrates a new approach to designing perovskites that balance both performance and durability. Published in Small, the findings mark a step forward in the pursuit of clean and cost-effective hydrogen production for sustainable energy systems.
Perovskites are a class of materials known for their remarkable ability to absorb light and transport electric charge, which makes them attractive for solar energy applications. However, traditional metal halide perovskites tend to break down when exposed to moisture, which limits their use in aqueous photocatalytic reactions such as hydrohalic-acid (HX) splitting for hydrogen generation.
To make these materials more stable, scientists have been exploring low-dimensional perovskites, structures where alternating organic and inorganic layers are arranged in a more confined form, such as sheets or chains. While this arrangement improves water resistance, it traps charge carriers within its layers, restricting their movement and lowering efficiency in solar-to-fuel conversion. Towards this, the IITGN team has synthesised a one-dimensional (1D) perovskite that enables better electronic connectivity while retaining high water stability. The developed perovskite uses a molecule called 4,4’-vinylenedipyridine (VDP) as a spacer between the inorganic layers of the perovskite. “This molecule links the structure electronically through pi-conjugation, a network of delocalised electrons that helps charges move more freely,” explained Dr Banerjee, Associate Professor at the Department of Physics and the Principal Investigator of the research. “It also reinforces stability through cation-pi interactions, which are attractive forces between positively charged ions and the electron-rich rings of VDP.”
The team synthesised and characterised two variants of the new low-dimensional perovskite, containing bromine and iodine, respectively. While bromine-based perovskites have been studied previously for similar applications, the iodide counterpart was synthesised for the first time in this work. Remarkably, both materials demonstrated exceptional durability by remaining intact even after being immersed in deionised (DI) water for over six months, with their crystal structure and optical properties unchanged. DI water, which is free from dissolved ions, provides a neutral and controlled environment that helps test a material’s true resistance to water-induced degradation.
When tested under simulated sunlight, the iodide-based material showed excellent photocatalytic activity, producing about 1.81 millimoles of hydrogen per gram of catalyst within 24 hours, without using any noble-metal co-catalyst. The hydrogen evolution occurred through the splitting of hydroiodic acid (HI) under simulated sunlight, confirming the material’s effectiveness in hydrohalic-acid photocatalysis. The bromide variant, however, did not generate hydrogen because its energy levels were not optimally aligned for the chemical reaction. “This contrast in the photocatalytic activity of the two variants highlights how subtle changes in the halide component can influence the light absorption and electronic alignment of the material,” said Dr Manoj Singh, former PhD student at IITGN and currently a postdoctoral researcher at the Indian Association for the Cultivation of Science, Kolkata.
The findings demonstrate that combining pi-conjugation and cation-pi interactions yields a 1D VDP perovskite that retains structural integrity in water while sustaining efficient hydrogen evolution. This molecular design approach offers valuable guidance for developing durable, high-performance perovskites for solar-driven hydrogen generation.
“As the world moves toward sustainable and scalable energy solutions, semiconducting materials like halide perovskites are increasingly recognised for their potential in advancing solar-driven hydrogen production technologies,” noted Dr Banerjee. “By eliminating the need for rare and expensive noble-metal co-catalysts and ensuring long-term stability in aqueous environments, our lead-halide perovskite marks a significant step toward scalable, sustainable hydrogen production. The advancement could support global clean-energy efforts and accelerate progress toward net-zero goals.”
The co-authors of the study include Prof Gwladys Pourceau, Dr Lucie Quéhon, and Prof Frédéric Sauvage.