Peiyang Zhao

CsPb0.9Sn0.1IBr2 Based All-Inorganic Perovskite Solar Cells with Exceptional Efficiency and Stability

The emergence of perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. Recently, cesium metal halides (CsMX3, M = Pb or Sn; X = I, Br, Cl or mixed halides) as a class of inorganic perovskites showed great promise for PSCs and other optoelectronic devices. However, CsMX3-based PSCs usually exhibit lower power conversion efficiencies (PCEs) than organic-inorganic hybrid PSCs, due to the unfavorable band gaps. Herein, a novel mixed-Pb/Sn mixed-halide inorganic perovskite, CsPb0.9Sn0.1IBr2, with a suitable band gap of 1.79 eV and an appropriate level of valence band maximum, was prepared in ambient atmosphere without a glovebox. After thoroughly eliminating labile organic components and noble metals, the all-inorganic PSCs based on CsPb0.9Sn0.1IBr2 and carbon counter electrodes exhibit a high open-circuit voltage of 1.26 V and a remarkable PCE up to 11.33%, which is record-breaking among the existing CsMX3-based PSCs. Moreover, the all-inorganic PSCs show good long-term stability and improved endurance against heat and moisture. This study indicates a feasible way to design inorganic halide perovskites through energy-band engineering for the construction of high-performance all-inorganic PSCs.

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium–Sulfur Batteries

Lithium-sulfur (Li-S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li-S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1-3 mg cm-2) and thus cannot fulfill the requirement for practical deployment. Herein, we report that porous-shell vanadium nitride nanobubbles (VN-NBs) can serve as an efficient sulfur host in Li-S batteries, exhibiting remarkable electrochemical performances even with ultrahigh areal sulfur loading weights (5.4-6.8 mg cm-2). The large inner space of VN-NBs can afford a high sulfur content and accommodate the volume expansion, and the high electrical conductivity of VN-NBs ensures the effective utilization and fast redox kinetics of polysulfides. Moreover, VN-NBs present strong chemical affinity/adsorption with polysulfides and thus can efficiently suppress the shuttle effect via both capillary confinement and chemical binding, and promote the fast conversion of polysulfides. Benefiting from the above merits, the Li-S batteries based on sulfur-filled VN-NBs cathodes with 5.4 mg cm-2 sulfur exhibit impressively high areal/specific capacity (5.81 mAh cm-2), superior rate capability (632 mAh g-1 at 5.0 C), and long cycling stability.

Interface Engineering of Anchored Ultrathin TiO2/MoS2 Heterolayers for Highly-Efficient Electrochemical Hydrogen Production

An efficient self-standing hydrogen evolution electrode was prepared by in situ growth of stacked ultrathin TiO2/MoS2 heterolayers on carbon paper (CP@TiO2@MoS2). Owing to the high overall conductivity, large electrochemical surface area and abundant active sites, this novel electrode exhibits an excellent performance for hydrogen evolution reaction (HER). Remarkably, the composite electrode shows a low Tafel slope of 41.7 mV/dec, and an ultrahigh cathodic current density of 550 mA/cm2 at a very low overpotential of 0.25 V. This work presents a new universal strategy for the construction of effective, durable, scalable, and inexpensive electrodes that can be extended to other electrocatalytic systems.

Integrated perovskite solar capacitors with high energy conversion efficiency and fast photo-charging rate

Integrating energy harvesting devices with energy storage systems can realize a temporal buffer for local power generation and power consumption. In this manner, self-charging energy devices consisting of photovoltaic cells and energy storage units can serve as sustainable and portable distributed power sources that can concurrently generate and store electric energy without the need for external charging circuits. Herein, an integrated perovskite solar capacitor (IPSC) was realized by combining a perovskite solar cell (PSC) and a supercapacitor in a single device. Taking advantages of nanocarbon electrodes, the IPSCs possess a simple configuration, compact structure, and well-matched operation voltage. The IPSCs could be rapidly charged by different modes (including the photo-charging mode, galvanostatic-charging mode, and photoassisted-galvanostatic-charging mode), and showed a remarkable overall photo-chemical-electricity energy conversion efficiency as high as 7.1% in the photo-charging mode. Moreover, the IPSCs could work efficiently under weak light illumination. This study provides new insights for the design of novel integrative energy devices that combine the functions of solar power harvesting and electrochemical energy storage.

Three-dimensional spongy framework as superlyophilic, strongly absorbing, and electrocatalytic polysulfide reservoir layer for high-rate and long-cycling lithium-sulfur batteries

In the development of lithium-sulfur (Li-S) batteries, various approaches have been adopted to enhance the electronic conductivity of the sulfur cathode and alleviate the shuttle effect of polysulfides; however, the strategies providing efficient solutions are still limited. To further improve the electrochemical performance of Li-S batteries, in this work we propose a new strategy involving the incorporation of a three-dimensional functional spongy framework as polysulfide reservoir layer, with strong absorbability and electrocatalytic activity towards sulfur species. The spongy framework has a hierarchical architecture composed of highly conductive Ni foam/graphene/carbon nanotubes/MnO2 nanoflakes (NGCM). The strongly interconnected Ni foam, graphene, and carbon nanotubes of the NGCM sponge facilitate electron transfer during discharge/charge processes; moreover, the superlyophilic properties of the NGCM sponge ensure good wettability and interface contact with the Li-S electrolyte, and the porous MnO2 nanoflakes provide strong chemisorptive and electrocatalytic effects on polysulfides (as confirmed theoretically and experimentally). The NGCM sponge, serving as a polysulfide reservoir layer attached on a conventional sulfur-mixed carbon nanotubes (S/CNTs) cathode, can provide improved reversible capacity, rate capability (593 mAh·g–1 at 3.0 C), and cycling stability. In addition, the self-discharge rate is greatly reduced, owing to the efficient conservation of polysulfides in the NGCM spongy framework.

Highly efficient overall water splitting driven by all-inorganic perovskite solar cells and promoted by bifunctional bimetallic phosphide nanowire arrays

Overall water splitting driven by a sustainable solar energy source has been recognized as a promising route to produce clean and renewable hydrogen fuel. However, its practical application is restricted by the low energy conversion efficiency and poor stability of photocatalysts. Herein, we report the realization of highly efficient overall water splitting promoted by bifunctional bimetallic phosphide (Ni0.5Co0.5P) nanowire arrays vertically grown on carbon paper (Ni0.5Co0.5P/CP) and driven by highly stable all-inorganic perovskite solar cells (PSCs). The Ni0.5Co0.5P/CP electrocatalysts can provide abundant active sites, high electrical conductivity, and good contact interface with the electrolyte, thus showing remarkable activity and great durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The electrolyzer assembled with both the Ni0.5Co0.5P/CP anode and cathode can afford a current density of 10 mA cm−2 at only 1.61 V and allow consecutive water splitting. The all-inorganic PSCs based on a CsPb0.9Sn0.1IBr2 light absorber and a nanocarbon electrode exhibit remarkable stability. When driven by all-inorganic PSCs, the electrolyzer delivers a high overall energy conversion efficiency (3.12%) and good long-term durability.