A Z‐scheme heterojunction with spatially separated cocatalysts is proposed for overcoming fundamental issues in photocatalytic water splitting, such as inefficient light absorption, charge recombination, and sluggish reaction kinetics. For efficient light absorption and interfacial charge separation, Z‐scheme organic/inorganic heterojunction photocatalysts are synthesized by firmly immobilizing ultrathin g‐C3N4 on the surface of TiO2 hollow spheres via electrostatic interactions. Additionally, two cocatalysts, Pt and IrOx, are spatially separated along the Z‐scheme charge‐transfer pathway to enhance surface charge separation and reaction kinetics. The as‐prepared Pt/g‐C3N4/TiO2/IrOx (PCTI) hollow sphere photocatalyst exhibits an exceptional H2 evolution rate of 8.15 mmol h−1 g−1 and a remarkable apparent quantum yield of 24.3% at 330 nm in the presence of 0.5 wt% Pt and 1.2 wt% IrOx cocatalysts on g‐C3N4 and TiO2, respectively. Photoassisted Kelvin probe force microscopy is used to systematically analyze the Z‐scheme charge‐transfer mechanism within PCTI. Furthermore, the benefits of spatially separating cocatalysts in the PCTI system are methodically investigated in comparison to randomly depositing them. This work adequately demonstrates that the combination of a Z‐scheme heterojunction and spatially separated cocatalysts can be a promising strategy for designing high‐performance photocatalytic platforms for solar fuel production.

Anionic and cationic defects are considered as one of the crucial factors that affect carrier transport property and degradation of perovskite photovoltaic materials. Herein, we demonstrate a simple passivation of hot casted perovskite film in air by a dipolar ion, 2-thiophene ethylammonium chloride (TEACl), showing enhanced power conversion efficiency (PCE) of solar cell from 15.44% to 18.84% with increased open circuit voltage (V oc) by 50 mV. The dipolar ion of TEACl can simultaneously passivate both cationic and anionic defects. Space charge limited current model, Urbach energy analysis, and photoluminescence spectroscopy were conducted and revealed that the defects passivated by TEACl reduced the defects density of perovskite films, nonradiative recombination, and electronic disorder. In addition, the device with TEACl passivation exhibited outstanding stability of power output (<0.1% decay) as compared with the device without passivation (>8% decay) from the 300 s measurement of current verse time plots (J–T plots) at 65% relative humidity and 50 °C in air. The 80% of initial PCE was maintained after 700 h storage. As compared to conventional passivation approaches which are typically carried out at complicated crystallization step of perovskite, this post-treatment process can be easily done on the crystallized perovskite film. This facile approach is upscale and compatible with conventional coating techniques such as slot-die coating, spray, etc. for high-quality perovskite film.

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We develop a universal hydroxide-assisted strategy for the low thermal budget efficient fabrication of high quality metal oxide thin films.

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Hydrogenated titanium dioxide has attracted intensive research interests in pollutant removal applications due to its high photocatalytic activity. Herein, we demonstrate hydrogenated TiO2 nanofibers (H:TiO2 NFs) with a core-shell structure prepared by the hydrothermal synthesis and subsequent heat treatment in hydrogen flow. H:TiO2 NFs has excellent solar light absorption and photogenerated charge formation behavior as confirmed by optical absorbance, photo-Kelvin force probe microscopy and photoinduced charge carrier dynamics analyses. Photodegradation of various organic dyes such as methyl orange, rhodamine 6G and brilliant green is shown to take place with significantly higher rates on our novel catalyst than on pristine TiO2 nanofibers and commercial nanoparticle based photocatalytic materials, which is attributed to surface defects (oxygen vacancy and Ti3+ interstitial defect) on the hydrogen treated surface. We propose three properties/mechanisms responsible for the enhanced photocatalytic activity, which are: (1) improved absorbance allowing for increased exciton generation, (2) highly crystalline anatase TiO2 that promotes fast charge transport rate, and (3) decreased charge recombination caused by the nanoscopic Schottky junctions at the interface of pristine core and hydrogenated shell thus promoting long-life surface charges. The developed H:TiO2 NFs can be helpful for future high performance photocatalysts in environmental applications.

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