Stabilizing Metal Halide Perovskites for Solar Fuel Production: Challenges, Solutions, and Future Prospects

Strengthening Bonding Interaction of a (Co0.91V0.09)3(BTC)2 Metal-Organic Framework with BiVO4 Photoanodes Enabling Ultrastable Photoelectrochemical Water Oxidation

Although the oxygen evolution reaction (OER) activity of BiVO4 photoanodes has been significantly enhanced, achieving long-term photostability is still challenging due to the gradual dissolution of V5+ during photoelectrochemical (PEC) water splitting. Herein, we deliberately generate ligand defects in a (Co0.91V0.09)3(BTC)2 metal-organic framework (CoV-MOF) that creates more undercoordinated sites, forming strong chemical bonds with BiVO4. Consequently, the dissolution of V5+ from BiVO4 during PEC water splitting can be effectively suppressed, leading to significantly enhanced stability. The optimized Co3O4/CoV-MOF/BiVO4 photoanode exhibits a high photocurrent density of 6.0 mA cm-2 at 1.23 V vs the reversible hydrogen electrode (RHE). Impressively, the photoanode can stably operate for 500 h at 0.6 V vs RHE under AM 1.5 G illumination. This work demonstrates the proof-of-concept of anchoring V5+ in BiVO4 photoanodes achieving ultrastable PEC water splitting.

Interface Engineering, Charge Carrier Dynamics, and Solar-Driven Applications of Halide Perovskite/2D Material Heterostructured Photocatalysts

Halide perovskites (HPs), renowned for their intriguing optoelectronic properties, such as robust light absorption coefficient, long charge transfer distance, and tunable band structure, have emerged as a focal point in the field of photocatalysis. However, the photocatalytic performance of HPs is still inhibited by rapid charge recombination, insufficient band potential energy, and limited number of surface active sites. To overcome these limitations, the integration of two-dimensional (2D) materials, characterized by shortened charge transfer pathways and expansive surface areas, into HP/2D heterostructures presents a promising avenue to achieve exceptional interfacial properties, including extensive light absorption, efficient charge separation and transfer, energetic redox capacity, and adjustable surface characteristics. Herein, a comprehensive review delving into fundamentals, interfacial engineering, and charge carrier dynamics of HP/2D material heterostructures is presented. Numerous HP/2D material photocatalysts fabricated through diverse strategies and interfacial architectures are systematically described and categorized. More importantly, the enhanced charge carrier dynamics and surface properties of the HP/2D material heterostructures are thoroughly investigated and discussed. Finally, an analysis of the challenges faced in the development of HP/2D photocatalysts, alongside insightful recommendations for potential strategies to overcome these barriers, is provided.

Light-Driven Low-Temperature and Near-Unity Conversion of Ester on a Perovskite Derivative Photothermal Catalyst via Photon-Bismuth Triggered Hotspot

Solar-driven photothermal chemical transformations are regarded as green processes to reduce energy consumption and are expected to utilize unique light-induced activation mechanisms to improve reaction kinetics. Halide perovskites and their derivatives, due to unique optoelectronic properties and compositional flexibility, are allowed for the precise regulation of energy band structures and surface electronic states, showing potentials as photoactivated catalysts with photo-thermal synergistic effects. However, the photothermal catalytic performance of halide perovskites is still unsatisfied with low conversion (<0.2%). Herein, Cs3BixSb2- xBr9 is designed as a novel and effective photothermal catalyst for light-driven degradation of ester under room temperature, achieving a near-unity conversion of ≈99% without external heating. Photothermal catalytic process shows the remarkable enhancementup to 796% and 200% compared with that in the single thermocatalysis or photocatalysis. The stable catalyst shows superior light-driven cyclic performance, as well. Mechanistic studies combined with in situ characterizations and theoretical calculations show that photon-bismuth hotspot with the synergy of photoinduced charge transfer process (photochemistry) significantly reduce the activation energy, light-to-heat effects (thermochemistry) elevate the local temperature, and bismuth active site promotes the C─O bond activation (surface adsorption), which together contribute to excellent solar-driven conversion efficiency on the perovskite derivative.

Defects of Metal Halide Perovskites in Photocatalytic Energy Conversion: Friend or Foe?

Photocatalytic solar-to-fuel conversion over metal halide perovskites (MHPs) has recently attracted much attention, while the roles of defects in MHPs are still under debate. Specifically, the mainstream viewpoint is that the defects are detrimental to photocatalytic performance, while some recent studies show that certain types of defects contribute to photoactivity enhancement. However, a systematic summary of why it is contradictory and how the defects in MHPs affect photocatalytic performance is still lacking. In this review, the innovative roles of defects in MHP photocatalysts are highlighted. First, the origins of defects in MHPs are elaborated, followed by clarifying certain benefits of defects in photocatalysts including optical absorption, charge dynamics, and surface reaction. Afterward, the recent progress on defect-related MHP photocatalysis, i.e., CO2 reduction, H2 generation, pollutant degradation, and organic synthesis is systematically discussed and critically appraised, putting emphasis on their beneficial effects. With defects offering peculiar sets of merits and demerits, the personal opinion on the ongoing challenges is concluded and outlining potentially promising opportunities for engineering defects on MHP photocatalysts. This critical review is anticipated to offer a better understanding of the MHP defects and spur some inspiration for designing efficient MHP photocatalysts.

Comparison of perinatal and neonatal outcomes of symptomatic pregnancy infected with SARS-CoV-2

Objective

In this study, maternal and neonatal outcomes of pregnant women with positive severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) RNA tests were evaluated according to their symptomatic status. The clinical progression of SARS-CoV-2-positive pregnant women and the effect of coronavirus disease-2019 (COVID-19) on newborns was investigated.

Material and Methods

This retrospective cohort study was conducted at a tertiary pandemic hospital specializing in caring for pregnant women infected with SARS-CoV-2. We included patients with a positive SARS-CoV-2 polymerase chain reaction test at delivery, subdividing them into symptomatic and asymptomatic groups.

Results

Two hundred and forty-nine patients were included in the study. The mean age of the pregnant women in the symptomatic group was higher than those in the asymptomatic group (p=0.001). The iatrogenic preterm birth rates in the symptomatic and asymptomatic groups were 43.37% and 8.43%, respectively (p<0.001). Cesarean section rate was higher in symptomatic group (p=0.01). Maternal death was significantly higher in symptomatic pregnant women (p<0.001). The neonatal intensive care unit admission rate was higher in symptomatic pregnant women (p<0.001).

Conclusion

The maternal and fetal outcomes for mothers with symptomatic infections tend to be worse, highlighting the importance of careful management, good follow-up and the advisability of closer monitoring.

All-Inorganic Perovskite Solar Cells: Defect Regulation and Emerging Applications in Extreme Environments

All-inorganic perovskite solar cells (PSCs), such as CsPbX3, have garnered considerable attention recently, as they exhibit superior thermodynamic and optoelectronic stabilities compared to the organic-inorganic hybrid PSCs. However, the power conversion efficiency (PCE) of CsPbX3 PSCs is generally lower than that of organic-inorganic hybrid PSCs, as they contain higher defect densities at the interface and within the perovskite light-absorbing layers, resulting in higher non-radiative recombination and voltage loss. Consequently, defect regulation has been adopted as an important strategy to improve device performance and stability. This review aims to comprehensively summarize recent progresses on the defect regulation in CsPbX3 PSCs, as well as their cutting-edge applications in extreme scenarios. The underlying fundamental mechanisms leading to the defect formation in the crystal structure of CsPbX3 PSCs are firstly discussed, and an overview of literature-adopted defect regulation strategies in the context of interface, internal, and surface engineering is provided. Cutting-edge applications of CsPbX3 PSCs in extreme environments such as outer space and underwater situations are highlighted. Finally, a summary and outlook are presented on future directions for achieving higher efficiencies and superior stability in CsPbX3 PSCs.

Semimetallic Bismuthene with Edge-Rich Dangling Bonds: Broad-Spectrum-Driven and Edge-Confined Electron Enhancement Boosting CO2 Hydrogenation Reduction

Broad-spectrum-driven high-performance artificial photosynthesis is quite challenging. Herein, atomically ultrathin bismuthene with semimetallic properties is designed and demonstrated for broad-spectrum (ultraviolet-visible-near infrared light) (UV-vis-NIR)-driven photocatalytic CO2 hydrogenation. The trap states in the bandgap produced by edge dangling bonds prolong the lifetime of the photogenerated electrons from 90 ps in bulk Bi to 1650 ps in bismuthine, and excited-state electrons are enriched at the edge of bismuthine. The edge dangling bonds of bismuthene as the active sites for adsorption/activation of CO2 increase the hybridization ability of the Bi 6p orbital and O 2p orbital to significantly reduce the catalytic reaction energy barrier and promote the formation of C─H bonds until the generation of CH4. Under λ ≥ 400 nm and λ ≥ 550 nm irradiation, the utilization ratios of photogenerated electron reduction CO2 hydrogenation to CO and CH4 for bismuthene are 58.24 and 300.50 times higher than those of bulk Bi, respectively. Moreover, bismuthene can extend the CO2 hydrogenation reaction to the near-infrared region (λ ≥ 700 nm). This pioneering work employs the single semimetal element as an artificial photosynthetic catalyst to produce a broad spectral response.

Recent Advances in Carbon Nanotube Utilization in Perovskite Solar Cells: A Review

Due to their exceptional optoelectronic properties, halide perovskites have emerged as prominent materials for the light-absorbing layer in various optoelectronic devices. However, to increase device performance for wider adoption, it is essential to find innovative solutions. One promising solution is incorporating carbon nanotubes (CNTs), which have shown remarkable versatility and efficacy. In these devices, CNTs serve multiple functions, including providing conducting substrates and electrodes and improving charge extraction and transport. The next iteration of photovoltaic devices, metal halide perovskite solar cells (PSCs), holds immense promise. Despite significant progress, achieving optimal efficiency, stability, and affordability simultaneously remains a challenge, and overcoming these obstacles requires the development of novel materials known as CNTs, which, owing to their remarkable electrical, optical, and mechanical properties, have garnered considerable attention as potential materials for highly efficient PSCs. Incorporating CNTs into perovskite solar cells offers versatility, enabling improvements in device performance and longevity while catering to diverse applications. This article provides an in-depth exploration of recent advancements in carbon nanotube technology and its integration into perovskite solar cells, serving as transparent conductive electrodes, charge transporters, interlayers, hole-transporting materials, and back electrodes. Additionally, we highlighted key challenges and offered insights for future enhancements in perovskite solar cells leveraging CNTs.

Superalkali halide perovskites with suitable direct band gaps for photovoltaic applications

The construction of superalkali halide perovskites has attracted attention for the development of new photovoltaic materials, but stable superalkalis have not been found until now. Herein, to construct new three-dimensional superalkali halide perovskites with a MI3 frame (M = Sn and Pb), a new Li(H2O)3+ superalkali cation is designed and selected based on low vertical ionization potential, suitable tolerance factor, small ionic radius and large dissociation energy. High-throughput first-principles calculations show that superalkalis with lower vertical ionization potentials exhibit stronger interactions with the MI3 frame. The normal and cubic Li(H2O)3MI3 perovskites and cubic Li(H2O)4PbI3 perovskites have direct band gaps, s-p and p-p electron transitions, effective carrier masses of less than 0.45me and exciton binding energies of less than 291 meV. Moreover, the cubic Li(H2O)3PbI3 perovskite with a direct band gap of 1.40 eV can in theory show a power conversion efficiency of 33.49%. These results strongly suggest that superalkali cations with large dissociation energy can be used to develop stable superalkali perovskites for photovoltaic applications.