Prussian blue analogues with tunable electron structure by different transition metal salts for wide spectrum photocatalytic hydrogen evolution

Abstract

Photocatalytic hydrogen evolution is regarded as an efficient approach to fulfill future energy requirements. Prussian blue analogues (PBAs) serving as distinctive Metal-organic frameworks, feature a multi-electron, multi-core structure, as well as exceptional properties like structural stability and compositional adjustability. These attributes endow them with significant promise in the realm of photocatalytic hydrogen evolution. In this work, the six kinds of common transition metal salts were employed in synthesizing Prussian blue analogues (Cd–Co PBAs, Cu–Co PBAs, Co–Co PBAs, Ni–Co PBAs, Zn–Co PBAs and In–Co PBAs) featuring varying metal compositions through the chemical co-precipitation method. A comprehensive analysis was subsequently carried out to explore the connection between their structural features and properties. The six kinds of Prussian blue analogues were directly used as catalysts to evaluate their performance in photocatalytic hydrogen evolution, accompanied by a thorough investigation into the impact of their structural variations on their ability to facilitate photocatalytic hydrogen evolution. Among them, Ni–Co PBAs has the highest photocatalytic hydrogen evolution rate (6197.4 μmol h−1 g−1) and the highest apparent quantum efficiency (AQE) of 5.75 % at 475 nm due to the suitable band gap structure and the ideal MII/MIII atomic ratio (3:2). When explaining the correlation between electronic structure and properties of PBAs, the density functional theory (DFT) calculation gives further insight. This work provides a comprehensive understanding of the structure and properties of PBAs, which will provide a sustainable strategy for the development of photocatalysts based on PBAs for achieving high conversion efficiency of solar energy into hydrogen energy.