Stable Cs₂ReX₆ (X – Cl, Br) vacancy-ordered perovskites for solar water splitting

Abstract

In this work, we report two vacancy ordered perovskites based on Cs2ReX6 (X - Cl, Br) for stable solar water oxidation. Instability of halide perovskites in aqueous media restricts their...

Mixed‐Tetravalent Cs2RumPt1−mX6 (X = Cl−, Br−)‐Based Vacancy‐Ordered Halide Double Perovskites for Enhanced Solar Water Oxidation

“…These experiments also point to the stability of material until pH11.This aqueous stability between pH1 and pH11 will enable them to be employed as absorbers in solar PEC water splitting, where harsh pH electrolytes are typically used for water-oxidation/reduction reactions. [10,45,46] Only few materials under vacancy-ordered perovskite class of materials including Cs 2 PtX 6 , [29,31] Cs 2 ReX 6 , [30] and Cs 2 OsX 6 [33] (X is a halide ion) have shown to be stable, unlike conventional ABX 3 systems which easily degrades in aqueous medium. [47][48][49] The mixed-tetravalent cationic site is also expected to affect the thermal properties of these materials.…”

“…In the past, our group have employed these materials Cs 2 MX 6 (M = Pt, Re, Os) as photoanodes and successfully demonstrated water splitting. [29][30][31][32][33] In this work, we report the PEC water splitting based on Cs 2 RuX 6 (X-Cl, Br) with Pt being substituted in the Ru site. The Pt-based materials deliver excellent photovoltage, while the presence of Ru enhanced the charge transfer from absorber to electrolyte.…”

“…Similar stability was obtained for Cl and Br variant of Cs 2 PtX 6 . [ 31 ] This extraordinary basic pH stability was not even observed in Cs 2 OsX 6 , [ 33 ] and Cs 2 ReX 6 , [ 30 ] perovskites. This motivated us to incorporate the platinum cation in ruthenium‐based VOP to obtain synergic effects of both the materials.…”

Biocompatible Cs2PtX6 (X = Cl, Br, I) Vacancy Ordered Perovskites and Shewanella oneidensis MR-1 Bacteria Hybrid for Potential Photocatalytic Solar Fuel Production

“…Essentially, these high quality optoelectronic materials are ruled out from any semiconductor–microbe hybrid systems for photocatalytic reactions. However, their subclass of materials, called vacancy ordered halide double perovskites (VOP) with A +1 2 B 4+ X 6 (A = Cs; B = Pt, Pd, Ru, Os, Re; X = halide), is found to be stable even in harsh pH conditions without decomposition. − The VOP materials show panchromatic light absorption covering the entire visible region with some of them even penetrating into the NIR and were successfully employed in solar water oxidation reactions. − It is wise to employ these materials as a replacement for ABX 3 perovskite, oxides, or sulfides in inorganic–bio hybrid photochemical systems for enhanced solar-to-fuel conversion. As this hybrid system is based on living microbes, the biocompatibility of microbes with VOP is important.…”