We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FACsSnPbI, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FACsPb(IBr) material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable "all-perovskite" thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

As the record single-junction efficiencies of perovskite solar cells now rival those of CIGS, CdTe, and multicrystalline silicon, they are becoming increasingly attractive for use in tandem solar cells, due to their wide, tunable bandgap and solution processability. Previously, perovskite/silicon tandems were limited by significant parasitic absorption and poor environmental stability. Here, we improve the efficiency of monolithic, two-terminal, 1 cm 2 perovskite/silicon tandems to 23.6% by combining an infrared-tuned silicon heterojunction bottom cell with the recently developed cesium formamidinium lead halide perovskite. This more stable perovskite tolerates deposition of a tin oxide buffer layer via atomic layer deposition that prevents shunts, has negligible parasitic absorption, and allows for the sputter deposition of a transparent top electrode. Furthermore, the window layer doubles as a diffusion barrier, increasing the thermal and environmental stability to enable perovskite devices that withstand a 1000-hour damp heat test at 85 °C and 85% relative humidity.

A sputtered oxide layer enabled by a solution-processed oxide nanoparticle buffer layer to protect underlying layers is used to make semi-transparent perovskite solar cells. Single-junction semi-transparent cells are 12.3% efficient, and mechanically stacked tandems on silicon solar cells are 18.0% efficient. The semi-transparent perovskite solar cell has a T 80 lifetime of 124 h when operated at the maximum power point at 100 °C without additional sealing in ambient atmosphere under visible illumination.

Electrified membranes (EMs) have the potential to address inherent limitations of conventional membrane technologies. Recent studies have demonstrated that EMs exhibit enhanced functions beyond separation. Electrification could enhance the performance and sustainability of membrane technologies and stimulate new applications in water and wastewater treatment. Herein, we first describe EM materials, synthesis methods, electrofiltration modules, and operating modes. Next, we highlight applications of EMs in water decontamination, purification, and disinfection. Additionally, we discuss state-of-the-art electrification methods for controlling membrane organic fouling, biofouling, and inorganic scaling. We also evaluate the energy consumption of EMs for water treatment and fouling control. We conclude by discussing the challenges for improving the stability and practicality of EMs and by proposing pathways for future research and development. On the basis of our discussion, we suggest that EMs may be viable for ultrafiltration and microfiltration but not for salt-rejecting reverse osmosis and nanofiltration applications. Further, we find that EMs are promising for decontamination and organic fouling control, and these systems could be deployed for fit-for-purpose distributed treatment applications.

The importance of singlet oxygen (1O2) in the environmental and biomedical fields has motivated research for effective 1O2 production. Electrocatalytic processes hold great potential for highly-automated and scalable 1O2 synthesis, but they are energy- and chemical-intensive. Herein, we present a Janus electrocatalytic membrane realizing ultra-efficient 1O2 production (6.9 mmol per m3 of permeate) and very low energy consumption (13.3 Wh per m3 of permeate) via a fast, flow-through electro-filtration process without the addition of chemical precursors. We confirm that a superoxide-mediated chain reaction, initiated by electrocatalytic oxygen reduction on the cathodic membrane side and subsequently terminated by H2O2 oxidation on the anodic membrane side, is crucial for 1O2 generation. We further demonstrate that the high 1O2 production efficiency is mainly attributable to the enhanced mass and charge transfer imparted by nano- and micro-confinement effects within the porous membrane structure. Our findings highlight a new electro-filtration strategy and an innovative reactive membrane design for synthesizing 1O2 for a broad range of potential applications including environmental remediation.

Forward osmosis (FO), as an emerging technology for seawater desalination and wastewater reuse, has been attracting significant interest because of its energy efficiency. However, membrane fouling represents one of the major limitations for this technology, notably for thin film composite (TFC) polyamide (PA) membranes, which are prone to chlorine attack. In this study, silver nanoparticle (AgNPs)-decorated graphene oxide (GO) nanosheets (as an effective biocidal material) were covalently bonded to the PA surface to impart improved hydrophilicity and antibacterial properties to the membrane. AgNPs were synthesized in situ by the wet chemical reduction of silver nitrate onto the surface of GO nanosheets. The formation of the composite was verified by UV-vis spectroscopy, X-ray diffraction, and transmission electron microscopy techniques. The synthesized GO/Ag nanocomposites were then covalently bonded onto the TFC PA membrane surface using cysteamine through an amide forming condensation reaction.ATR-FTIR and XPS results confirmed the covalent bonding of the nanocomposite onto the TFC PA surface. Overall, the GO/Ag nanocomposite functionalized membranes exhibited super-hydrophilic properties (contact angles below 25°) and significant bacterial (E. coli) inactivation (over 95% in static bacterial inactivation tests) without adversely affecting the membrane transport properties. † Electronic supplementary information (ESI) available: FE-SEM and backscatter electron microscopy of (A) GO functionalized TFC and (B) GO/Ag nanocomposite functionalized TFC. Elements with high atomic numbers backscatter electrons more strongly than lighter elements with low atomic numbers and thus appear brighter on the image (Fig. S1). TEM images of (A) GO, (B) Ag NPs, and (C) GO/ Ag nanocomposite (Fig. S2). ATR-FTIR spectra of (A) a GO nanosheet and GO/Ag nanocomposite and (B) a control TFC and GO/Ag nanocomposite functionalized TFC membrane (Fig. S3). The zeta potential of the surface of the pristine and functionalized membranes as a function of solution pH. Measurements were taken at room temperature (23°C) in a solution of 1 mM KCl by adjusting pH with the dropwise addition of HCl and NaOH (Fig. S4). Surface roughness properties of pristine and GO/Ag functionalized TFC FO membranes (Table S1). XPS results for (A) pristine membrane and (B) cysteamine treated TFC FO membranes. Peaks at 198 eV for Cl2P and 162 for sulfur S2P are shown in (A) and (B), respectively (Fig. S5). Elemental composition of the membrane surface of pristine and functionalized membranes before and after sonication (Table S2). The physical stability of the silver NPs on the Ag NP decorated and GO/Ag functionalized membranes from XPS results. A 7 min bath sonication was applied to the membranes, and the percent of silver on the membrane surface was estimated (Fig. S6). SeeTo address the biofouling problem associated with thin film composite (TFC) forward osmosis (FO) membranes, we have developed novel surface coatings through covalent bonding of silver decorated grap...

Reactive membranes based on hydroxyl radical generation are hindered by the need for chemical dosing and complicated module and material design. Herein, we utilize an electrochemical approach featuring in situ generation of reactive (radical) chlorine species (RCS) through anodization of chloride ions for membrane self-cleaning. A hybridized carbon nanotube (CNT)-functionalized ceramic membrane (h-CNT/CM), possessing high hydrophilicity, permeability, and conductivity, was fabricated. Using carbamazepine (CBZ) as a probe, we confirmed the presence of RCS in the electrified h-CNT/CM. The rapid and complete degradation of CBZ in a single-pass ultrafiltration indicates a high localized RCS concentration within the three-dimensional porous CNT interwoven layer. We further demonstrate that the electrogeneration of RCS is a critical prestep for free chlorine (HClO and ClO–) formation. The self-cleaning efficiency of the membrane after fouling with a model organic foulant (alginate) was assessed using an electrified cross-flow membrane filtration system. The fouled h-CNT/CM exhibits a near complete water flux recovery following a short (1 min) self-cleaning with an applied voltage of 3 or 4 V and feed solutions of 100 or 10 mM sodium chloride, respectively. Considering the superior performance of the RCS-mediated self-cleaning compared to conventional membrane chemical cleaning using sodium hypochlorite, our results exemplify an effective strategy for in situ electrogeneration of RCS to achieve a highly efficient membrane self-cleaning.

ambient energy. TENG is of great interest for capturing low-frequency mechanical energy due to its low cost in fabrication and excellent coupling effect (triboelectric effect and electrostatic induction). Different structures and triboelectric materials of tribo electric nanogenerators (TENGs) have been designed for harvesting mechanical energy of different form, e.g., water wave, wind, vibration, and biomechanical motion energy from the natural environment. [6][7][8][9][10][11][12] Recently, based on the artificial intelligence (AI) technology, autonomous car (driverless, self-driving, robotic) is an innovative vehicle that is capable of sensing its environment and navigating without human input. Driving safety early warning (DSEW) system is very important for in the cruising of autonomous vehicles, and it is a key technology that has been proposed and developing fast in this field. In fact, information cannot be provided without a strong efficient sensor network. TENGs could be harvesting vibrational/slide energy from a moving vehicle, as power sources and self-powered sensors for DSEW system. [13][14][15] However, there are some limitations to the previously different kinds of TENGs. First, the triboelectric materials' supporting surface is easy to be damaged during the contact and the separation, it is unable to support sliding friction for long periods. Second, most organic triboelectric materials Rapid advancements in multifunctional triboelectric nanogenerators (TENGs) for energy harvesting and self-powered sensing must be partnered with corresponding advances in durability and heat-resistance, especially under harsh working conditions. A device suitable for harsh environmental applications based on the wear-resistant triboelectric material is reported. The working modes of the harsh-environmental TENG (heTENG) are composed of freestanding and single electrode that enable both harvesting sliding/vibration energy and self-powered vibrational sensing. For the first time, a TENG possessing wear resistance, withstanding high temperature, and high hardness is achieved by employing micro-nanocomposite for triboelectric materials. It is demonstrated to be directly used as a key supporting part, such as automobile's brake pads. In addition, it is found that the heTENG outputs 221 V, 27.9 µA cm −2 , and 33.4 µC cm −2 . Furthermore, since heTENG is vibration-sensitive, the automobile's self-powered smart braking system and sensor network are developed successfully which can automatically provide a precise early-warning signals, such as a reminder for brake replacement, and an indicator for tire overloading, and pressure. This work shows a new strategy to enhance the performance of triboelectric materials, making it applicable to harsh environments, as well as potential applications in autonomous vehicles and industrial brakes.