Exceptionally stable green rust, a mixed-valent iron-layered double hydroxide, as an efficient solar photocatalyst for H2 production from ammonia borane

Abstract Green rust (GR) is a mixed-valent iron mineral and structurally constitutes a family of layered double hydroxides that have attracted widespread attention in environmental and energy applications. However, despite the ubiquity of GR in environments and its potential instrumental role in life’s emergence, its instability against oxidation has limited this material’s applications. Here, we report a new type of GR exhibiting excellent oxidation and chemical stabilities synthesized via a one-pot solvothermal reaction using iron(III) chloride and glycerol. We demonstrate that the GR has a crystallinity and layer charge density considerably higher than that of conventional GR. The high stability of the GR comes from the less defective particle surface and highly-dense interlayer structure that suppress oxygen reaching structural iron(II). This GR can be used as an efficient and durable solar photocatalyst for H2 production from ammonia borane, while other iron minerals and a benchmark TiO2 show little to no activity.