Graphite-protected CsPbBr3 perovskite photoanodes functionalised with water oxidation catalyst for oxygen evolution in water

Abstract

Metal-halide perovskites have been widely investigated in the photovoltaic sector due to their promising optoelectronic properties and inexpensive fabrication techniques based on solution processing. Here we report the development of inorganic CsPbBr 3 -based photoanodes for direct photoelectrochemical oxygen evolution from aqueous electrolytes. We use a commercial thermal graphite sheet and a mesoporous carbon scaffold to encapsulate CsPbBr 3 as an inexpensive and efficient protection strategy. We achieve a record stability of 30 h in aqueous electrolyte under constant simulated solar illumination, with currents above 2 mA cm −2 at 1.23 V RHE . We further demonstrate the versatility of our approach by grafting a molecular Ir-based water oxidation catalyst on the electrolyte-facing surface of the sealing graphite sheet, which cathodically shifts the onset potential of the composite photoanode due to accelerated charge transfer. These results suggest an efficient route to develop stable halide perovskite based electrodes for photoelectrochemical solar fuel generation.

Metal Halide Perovskites for Solar‐to‐Chemical Fuel Conversion

“…To date, many types of such layers have been implemented, including a Ni layer (8 nm), Field's metal (a fusible alloy that melts at ≈62 °C. ), Ti foil, an In‐Bi alloy layer and a mesoporous carbon/graphite sheet . In the following, we discuss these approaches by classifying them according to their target reactions, i.e., water oxidation, water reduction, and CO 2 reduction.…”

Evidence for tetranuclear bis-μ-oxo cubane species in molecular iridium-based water oxidation catalysts from XAS analysis

“…Importantly, a pyalk-modified bis-m-oxo Ir 4 O 4 cubane would be consistent with previously reported characterization data including 17 O NMR, EPR, UV-vis and resonance-Raman spectroscopies, 24 and shed new light on the mode of surface binding of these catalysts. [38][39][40] However, we caution that the kinetic role of such tetrameric resting states will have to be clarified prior to mechanistic interpretations. Recently a half order in [Ir] on the rate of O 2 evolution has been found for a range of pyalkligated Ir WOCs using NaIO 4 , implying a dominant dimeric resting state liberating small amounts of active monomer into the catalytic cycle.…”

Photoelectrochemical Water Splitting Reaction System Based on Metal-Organic Halide Perovskites

“…Conversely, as a method of using compact material deposition, Da et al [79] formed a passivation layer by sputtering ultrathin Ni layers (8 nm), and Tao et al [81] devised a cell using a passivation layer by depositing conductive carbon and silver paste through the doctor blade method. Kim et al [86] formed a passivation layer through the ALD process, and Poli et al [82] devised a stable perovskite-based PEC device using mesoporous carbon and a graphite sheet. Nevertheless, the use of perovskite as a PEC requires improved stability through the development of passivation technology, because of its low stability when compared to other PEC materials.…”

“…Photoanode devices using conductive carbon pastes do not require complex catalyst deposition processes, and offer superior stability using cheap carbon paste materials. Poli et al [82] designed a photoanode that could operate at a wide pH range (2-13) using CsPbBr 3 perovskite material and a commercial thermal graphite sheet (Figure 5c). The combined layer of 20 µm thick mesoporous carbon (m-c) and commercial hydrophobic graphite sheet (GS) prevented the perovskite layer from being degraded by water.…”

“…Kim et al [86] improved the stability of the photocathode device by forming a thin, compact layer through titanium atomic layer deposition (ALD); the device showed 75% photocurrent (10.5 mA/cm 2 ) in a strong acid solution (H 2 SO 4 ), even after 2 h (see Figure 11b). Finally, Poli et al [82] created a highly-stable photoanode through passivation using a mesoporous carbon and graphite sheet; the device was stable for 5 h in a pH 12.5 solution, and the photocurrent was increased from 1.5 mA/cm 2 to 2 mA/cm 2 . The device also showed a lifetime of 34 h in alkaline electrolyte, 23 h in a near-neutral solution, and 7.8 h in an acidic solution (see Figure 11c).…”