Rhenium anchored Ti3C2T x (MXene) nanosheets for electrocatalytic hydrogen production.

Atomically thin Ti3C2T x (MXene) nanosheets with rich termination groups, acting as active sites for effective functionalization, are used as an efficient solid support to host rhenium (Re) nanoparticles for the electrocatalytic hydrogen evolution reaction (HER). The newly designed electrocatalyst - Re nanoparticles anchored on Ti3C2T x MXene nanosheets (Re@Ti3C2T x ) - exhibited promising catalytic activity with a low overpotential of 298 mV to achieve a current density of 10 mV cm-2, while displaying excellent stability. In comparison, the pristine Ti3C2T x MXene requires higher overpotential of 584 mV to obtain the same current density. After being stored under ambient conditions for 30 days, Re@Ti3C2T x retained 100% of its initial catalytic activity for the HER, while the pristine Ti3C2T x retained only 74.8% of its initial value. According to our theoretical calculations using density functional theory, dual Re anchored MXene (Re@Ti3C2T x ) exhibits a near-zero value of Gibbs free energy (ΔG H* = -0.06 eV) for the HER, demonstrating that the presence of Re significantly enhances the electrocatalytic activity of MXene nanosheets. This work introduces a facile strategy to develop an effective electrocatalyst for electrocatalytic hydrogen production.

Highly Dispersed Ru Nanoparticles on Boron-Doped Ti3 C2 Tx (MXene) Nanosheets for Synergistic Enhancement of Electrocatalytic Hydrogen Evolution.

2D-layered materials have attracted increasing attention as low-cost supports for developing active catalysts for the hydrogen evolution reaction (HER). In addition, atomically thin Ti3 C2 Tx (MXene) nanosheets have surface termination groups (Tx : F, O, and OH), which are active sites for effective functionalization. In this work, heteroatom (boron)-doped Ti3 C2 Tx (MXene) nanosheets are developed as an efficient solid support to host ultrasmall ruthenium (Ru) nanoparticles for electrocatalytic HER. The quantum-mechanical first-principles calculations and electrochemical tests reveal that the B-doping onto 2D MXene nanosheets can largely improve the intermediate H* adsorption kinetics and reduce the charge-transfer resistance toward the HER, leading to increased reactivity of active sites and favorable electrode kinetics. Importantly, the newly designed electrocatalyst based on Ru nanoparticles supported on B-doped MXene (Ru@B-Ti3 C2 Tx ) nanosheets shows a remarkable catalytic activity with low overpotentials of 62.9 and 276.9 mV to drive 10 and 100 mA cm-2 , respectively, for the HER, while exhibiting excellent cycling stabilities. Moreover, according to the theoretical calculations, Ru@B-Ti3 C2 Tx exhibits a near-zero value of Gibbs free energy (ΔGH*  = 0.002 eV) for the HER. This work introduces a facile strategy to functionalize MXene for use as a solid support for efficient electrocatalysts.

Efficiency and stability enhancement of perovskite solar cells using reduced graphene oxide derived from earth-abundant natural graphite.

Graphene - two-dimensional (2D) sheets of carbon atoms linked in a honeycomb pattern - has unique properties that exhibit great promise for various applications including solar cells. Herein we prepared two-dimensional (2D) reduced graphene oxide (rGO) nanosheets from naturally abundant graphite flakes (obtained from Tuv aimag in Mongolia) using solution processed chemical oxidation and thermal reduction methods. As a proof of concept, we used our rGO as a hole transporting material (HTM) in perovskite solar cells (PSCs). Promisingly, the use of rGO in the hole transporting layer (HTL) not only enhanced the photovoltaic efficiency of PSCs, but also improved the device stability. In particular, the best performing PSC employing rGO nanosheets exhibited a power conversion efficiency (PCE) of up to 18.13%, while the control device without rGO delivered a maximum efficiency of 17.26%. The present work demonstrates the possibilities for solving PSC issues (stability) using nanomaterials derived from naturally abundant graphite sources.

Electrocatalytic Activity of a 2D Phosphorene-Based Heteroelectrocatalyst for Photoelectrochemical Cells.

Research into efficient synthesis, fundamental properties, and potential applications of phosphorene is currently the subject of intense investigation. Herein, solution-processed phosphorene or few-layer black phosphorus (FL-BP) sheets are prepared using a microwave exfoliation method and used in photoelectrochemical cells. Based on experimental and theoretical (DFT) studies, the FL-BP sheets are found to act as catalytically active sites and show excellent electrocatalytic activity for triiodide reduction in dye-sensitized solar cells. Importantly, the device fabricated based on the newly designed cobalt sulfide (CoSx ) decorated nitrogen and sulfur co-doped carbon nanotube heteroelectrocatalyst coated with FL-BP (FL-BP@N,S-doped CNTs-CoSx ) displayed an impressive photovoltaic efficiency of 8.31 %, outperforming expensive platinum based cells. This work paves the way for using phosphorene-based electrocatalysts for next-generation energy-storage systems.

Single-Walled Carbon Nanotubes Enhance the Efficiency and Stability of Mesoscopic Perovskite Solar Cells.

Carbon nanotubes are 1D nanocarbons with excellent properties and have been extensively used in various electronic and optoelectronic device applications including solar cells. Herein, we report a significant enhancement in the efficiency and stability of perovskite solar cells (PSCs) by employing single-walled carbon nanotubes (SWCNTs) in the mesoporous photoelectrode. It was found that SWCNTs provide both rapid electron transfer and advantageously shifts the conduction band minimum of the TiO2 photoelectrode and thus enhances all photovoltaic parameters of PSCs. The TiO2-SWCNTs photoelectrode based PSC device exhibited a power conversion efficiency (PCE) of up to 16.11%, while the device fabricated without SWCNTs displayed an efficiency of 13.53%. More importantly, we found that the SWCNTs in the TiO2 nanoparticles (TiO2 NPs) based photoelectrode suppress the hysteresis behavior and significantly enhance both the light and long-term storage stability of the PSC devices. The present work provides important guidance for future investigations in utilizing carbonaceous materials for solar cells.

Carbon Nanotubes in TiO2 Nanofiber Photoelectrodes for High-Performance Perovskite Solar Cells.

1D semiconducting oxides are unique structures that have been widely used for photovoltaic (PV) devices due to their capability to provide a direct pathway for charge transport. In addition, carbon nanotubes (CNTs) have played multifunctional roles in a range of PV cells because of their fascinating properties. Herein, the influence of CNTs on the PV performance of 1D titanium dioxide nanofiber (TiO2 NF) photoelectrode perovskite solar cells (PSCs) is systematically explored. Among the different types of CNTs, single-walled CNTs (SWCNTs) incorporated in the TiO2 NF photoelectrode PSCs show a significant enhancement (≈40%) in the power conversion efficiency (PCE) as compared to control cells. SWCNTs incorporated in TiO2 NFs provide a fast electron transfer within the photoelectrode, resulting in an increase in the short-circuit current (Jsc) value. On the basis of our theoretical calculations, the improved open-circuit voltage (Voc) of the cells can be attributed to a shift in energy level of the photoelectrodes after the introduction of SWCNTs. Furthermore, it is found that the incorporation of SWCNTs into TiO2 NFs reduces the hysteresis effect and improves the stability of the PSC devices. In this study, the best performing PSC device constructed with SWCNT structures achieves a PCE of 14.03%.

Phosphorene and Phosphorene-Based Materials - Prospects for Future Applications.

Phosphorene, a single- or few-layered semiconductor material obtained from black phosphorus, has recently been introduced as a new member of the family of two-dimensional (2D) layered materials. Since its discovery, phosphorene has attracted significant attention, and due to its unique properties, is a promising material for many applications including transistors, batteries and photovoltaics (PV). However, based on the current progress in phosphorene production, it is clear that a lot remains to be explored before this material can be used for these applications. After providing a comprehensive overview of recent advancements in phosphorene synthesis, advantages and challenges of the currently available methods for phosphorene production are discussed. An overview of the research progress in the use of phosphorene for a wide range of applications is presented, with a focus on enabling important roles that phosphorene would play in next-generation PV cells. Roadmaps that have the potential to address some of the challenges in phosphorene research are examined because it is clear that the unprecedented chemical, physical and electronic properties of phosphorene and phosphorene-based materials are suitable for various applications, including photovoltaics.

Ascidian tunicate extracts attenuate rheumatoid arthritis in a collagen-induced murine model.

Murine rheumatoid arthritis models are often used to investigate the potential therapeutic effects of candidate drugs. The present study has been conducted in order to investigate the therapeutic efficacy of ascidian tunicate extracts in a collagen-induced arthritis DBA1/J mice model. Four types of formulas, ascidian tunicate extracts (ATE), crude ascidian tunicate glycans (ATEC), ascidian tunicate extracts with licorice extracts (ATEL), and crude ascidian tunicate glycans with licorice extracts (ATECL) were orally administered into DBA/1J mice for 3 weeks and paw edema and thickness were evaluated. Changes in inflammatory proteins and cytokines levels were monitored in hind leg tissues by Western blot and quantitative PCR analysis. The oral administration of ascidian tunicate extracts alleviated paw edema and improved the histological hind leg cartilage status. The extracts also reduced the matrix metalloproteinase-9 (MMP-9) protein and prostaglandin E synthase (PGES) levels. In addition, the extracts-treated groups showed increased interleukin-10 (IL-10) levels compared with the non-treated group. These findings suggest that orally administered ascidian tunicate extracts might have potential therapeutic effects for the treatment of rheumatoid arthritis.