Terminal Groups-Dependent Near-Field Enhancement Effect of Ti3C2Tx Nanosheets.

Both multilayered (ML) and few-layered (FL) Ti3C2Tx nanosheets have been prepared through a typical etching and delaminating procedure. Various characterizations confirm that the dominant terminal groups on ML-Ti3C2Tx and FL-Ti3C2Tx are different, which have been assigned to O-related and hydroxyl groups, respectively. Such deviation of the dominant terminals results in the different physical and chemical performance and eventually makes the nanosheets have different potential applications. In particular, before coupling to Ag nanoparticles, ML-Ti3C2Tx can present stronger near-field enhancement effect; however, Ag/FL-Ti3C2Tx hybrid structure can confine stronger near-field due to the electron injection, which can be offered by the terminated hydroxyl groups.

Pd/MXene(Ti3C2Tx)/reduced graphene oxide hybrid catalyst for methanol electrooxidation.

A key challenge in developing direct methanol fuel cells is the fabrication of electrocatalysts with high activity and long durability. Herein, we report a performance enhanced electrocatalyst of nanoscale Pd on MXene (Ti3C2Tx) and reduced graphene oxide (rGO). The mass activity of Pd/Ti3C2Tx-rGO (1: 1) hybrid toward methanol oxidation reaction is 753 mA mg-1, which is 1.7 times than that of Pd/C (446 mA mg-1). Additionally, the current density of Pd/Ti3C2Tx-rGO (1:1) catalyst contains 212 mAmg-1 which is nine times higher than that of Pd/C (23 mA mg-1) after 7200 s. The Pd/Ti3C2Tx-rGO (1:1) catalyst exhibits excellent cycling stability and long-term life. These remarkable catalytic performances are attributed to the role of Ti3C2Tx and rGO in enhancing the catalytic activity surface area and rapid mass/charge transfer due to the synergistic effect between Pd and Ti3C2Tx/rGO.

Fabrication of CsxFA1-xPbI3 Mixed-Cation Perovskites via Gas-Phase-Assisted Compositional Modulation for Efficient and Stable Photovoltaic Devices.

Over the past few years, significant attention has been focused on HC(NH2)2PbI3 (FAPbI3) perovskite due to its reduced band gap and enhanced thermal stability compared with the most studied CH3NH3PbI3 (MAPbI3). However, FAPbI3 is sensitive to moisture and also encounters a serious structural phase-transition from photoactive α-phase to photoinactive δ-phase. Herein, we first develop a novel FAI gas-phase-assisted mixed-cation compositional modulation method to fabricate CsxFA1-xPbI3 perovskite solar cells (PSCs), and realize the structural stabilization of α-phase FAPbI3 with the incorporation of smaller inorganic Cs+ ions. Through the setting of different Cs+ contents (x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.50) along with a moderate FAI vapor deposition process, a series of CsxFA1-xPbI3 films with consistent compositions are fabricated, which perfectly resolves the main blocking problems of the conventional solution approach, such as difficulty in compositional control and rough film morphology. Meanwhile, we find that the Cs+ amount is crucial for generating phase-pure CsxFA1-xPbI3 (0 < x < 0.30) while higher contents result in phase segregation. Consequently, the optimum amount of Cs+ (x = 0.15) is verified, and Cs0.15FA0.85PbI3 shows the smallest unit cell volume and good moisture-resistant feature. Correspondingly, the highest power conversion efficiency (PCE) of 14.45% based on Cs0.15FA0.85PbI3 PSCs is successfully achieved in this work.

A novel transformation route from PbS to CH3NH3PbI3 for fabricating curved and large-area perovskite films.

We present a new transformation route from PbS to CH3NH3PbI3 for the facile preparation of perovskites with all kinds of shapes via vapor-assisted chemical bath deposition (VACBD). As such, curved and large-area CH3NH3PbI3 films with high quality are successfully achieved, which are suitable for the manufacturing scale-up of perovskite solar cells.

Solvent Engineering for Ambient-Air-Processed, Phase-Stable CsPbI3 in Perovskite Solar Cells.

Inorganic CsPbI3 perovskite solar cells (PSCs) owning comparable photovoltaic performance and enhanced thermal stability compared to organic-inorganic hybrid perovskites have attracted enormous interest in the past year. However, it is still a challenge to stabilize the desired black α-CsPbI3 perovskites in ambient air for photovoltaic applications. Herein, sequential solvent engineering including the addition of hydroiodic acid (HI) and subsequent isopropanol (IPA) treatment for fabricating stable and working CsPbI3 PSCs is developed, and a novel low-temperature phase-transition route from new intermediate Cs4PbI6 to stable α-CsPbI3 is also released for the first time. As such, the as-prepared PSCs give a relatively high power conversion efficiency (PCE) of 4.13% (reverse scan), and the steady-state power output of 1.88% is confirmed for the selected cell with an initial PCE of 3.13%. To the best of our knowledge, this is the first demonstration of fabricating CsPbI3 inorganic PSCs under fully open-air conditions.

Uniform, stable, and efficient planar-heterojunction perovskite solar cells by facile low-pressure chemical vapor deposition under fully open-air conditions.

Recently, hybrid perovskite solar cells (PSCs) have attracted extensive attention due to their high efficiency and simple preparing process. Herein, a facile low-pressure chemical vapor deposition (LPCVD) technology is first developed to fabricate PSCs, which can effectively reduce the over-rapid intercalating reaction rate and easily overcome this blocking issue during the solution process. As a result, the prepared uniform perovskite films exhibit good crystallization, strong absorption, and long carrier diffusion length. More strikingly, CH3NH3PbI3 absorbers by LPCVD demonstrate excellent moisture-resistant feature even under laser illumination and high-temperature conditions, which indicates that our proprietary method is very suitable for the future low-cost, nonvacuum production of the new generation photovoltaic devices. Finally, high efficiency of 12.73% is successfully achieved under fully open-air conditions. To the best of our knowledge, this is the first report of efficient PSCs with such a high humidity above 60%.