No abstract

A gas sensor is used to detect SF6 decomposed gases, which are related to insulation faults, to accurately assess the insulated status of electrical equipment. Graphene films (GrF) modified with Au nanoparticles are used as an adsorbent for the detection of H2S and SOF2, which are two characteristic products of SF6 decomposed gases. Sensing experiments are conducted at room temperature. Results demonstrate that Au‐modified GrF yields opposite responses to the tested gases and is thus considered a promising material for developing H2S‐ and SOF2‐selective sensors. The first‐principles approach is applied to simulate the interaction between the gases and Au‐modified GrF systems and to interpret experimental data. The observed opposite resistance responses can be attributed to the charge‐transfer differences related to the interfacial interaction between the gases and systems. The density of states and Mulliken population analysis results confirm the apparent charge transfer in Au‐modified GrF chemisorption, whereas the van der Waals effect dominates the pristine graphene adsorption systems. Calculation results can also explicate the significant SOF2 responses on Au‐modified GrF. This work is important in graphene modulation and device design for selective detection.

The microstructures of photo‐ and counter‐electrodes play critical roles in the performance of dye‐sensitized solar cells (DSSCs). In particular, various interfaces, such as fluorinated‐tin oxide (FTO)/TiO2, TiO2/TiO2, and TiO2/electrolyte, in DSSCs significantly affect the final power conversion efficiency (PCE). However, research has generally focused more on the design of various nanostructured semiconducting materials with emphasis on optimizing chemical or/and physical properties, and less on these interface functionalizations for performance improvement. This work explores a new application of graphene to modify the interface of FTO/TiO2 to suppress charge recombination. In combination with interfaces functionalization of TiO2/TiO2 for low charge‐transport resistance and high charge‐transfer rate, the final PCE of DSSC is remarkably improved from 5.80% to 8.13%, achieving the highest efficiency in comparison to reported graphene/TiO2‐based DSSCs. The method of using graphene to functionalize the surface of FTO substrate provides a better alternative method to the conventional pre‐treatment through hydrolyzing TiCl4 and an approach to reduce the adverse effect of microstructural defect of conducting glass substrate for electronic devices.

Unique metal sulfide (MS) clusters embedded ultrathin nanosheets of Fe/Ni metal-organic framework (MOF) are grown on nickel foam (NiFe-MS/MOF@NF) as a highly efficient bifunctional electrocatalyst for overall water splitting. It exhibits remarkable catalytic activity and stability toward both the oxygen evolution reaction (OER, ƞ = 230 mV at 50 mA cm −2) and hydrogen evolution reaction (HER, ƞ = 156 mV at 50 mA cm −2) in alkaline media, and bi-functionally catalyzes overall alkaline water splitting at a current density of 50 mA cm −2 by 1.74 V cell voltage without iR compensation. The enhancement mechanism is ascribed to the impregnated metal sulfide clusters in the nanosheets, which not only promote the formation of ultrathin nanosheet to greatly enlarge the reaction surface area while offering high electric conductivity, but more importantly, efficiently modulate the electronic structure of the catalytically active atom sites to an electron-rich state via strong electronic interaction and strengthen the adsorption of oxygenate intermediate to facilitate fast electrochemical reactions. This work reports a highly efficient HER/OER bifunctional electrocatalyst and may shed light on the rational design and synthesis of uniquely structured MOF-derived catalysts.