Exploring new materials is essential in the field of material science. Especially, searching for optimal materials with utmost atomic utilization, ideal activities and desirable stability for catalytic applications requires smart design of materials’ structures. Herein, we report iridium metallene oxide: 1 T phase-iridium dioxide (IrO2) by a synthetic strategy combining mechanochemistry and thermal treatment in a strong alkaline medium. This material demonstrates high activity for oxygen evolution reaction with a low overpotential of 197 millivolt in acidic electrolyte at 10 milliamperes per geometric square centimeter (mA cmgeo−2). Together, it achieves high turnover frequencies of 4.2 sUPD−1 (3.0 sBET−1) at 1.50 V vs. reversible hydrogen electrode. Furthermore, 1T-IrO2 also shows little degradation after 126 hours chronopotentiometry measurement under the high current density of 250 mA cmgeo−2 in proton exchange membrane device. Theoretical calculations reveal that the active site of Ir in 1T-IrO2 provides an optimal free energy uphill in *OH formation, leading to the enhanced performance. The discovery of this 1T-metallene oxide material will provide new opportunities for catalysis and other applications.

Currently, platinum-based electrocatalysts show the best performance for hydrogen evolution. All hydrogen evolution reaction catalysts should however obey Sabatier's principle, that is, the adsorption energy of hydrogen to the catalyst surface should be neither too high nor too low to balance between hydrogen adsorption and desorption. To overcome the limitation of this principle, here we choose a composite (rhodium/silicon nanowire) catalyst, in which hydrogen adsorption occurs on rhodium with a large adsorption energy while hydrogen evolution occurs on silicon with a small adsorption energy. We show that the composite is stable with better hydrogen evolution activity than rhodium nanoparticles and even exceeding those of commercial platinum/carbon at high overpotentials. The results reveal that silicon plays a key role in the electrocatalysis. This work may thus open the door for the design and fabrication of electrocatalysts for high-efficiency electric energy to hydrogen energy conversion.

Artificial photosynthesis of H2O2 from H2O and O2, as a spotless method, has aroused widespread interest. Up to date, most photocatalysts still suffer from serious salt-deactivated effects with huge consumption of photogenerated charges, which severely limit their wide application. Herein, by using a phenolic condensation approach, carbon dots, organic dye molecule procyanidins and 4-methoxybenzaldehyde are composed into a metal-free photocatalyst for the photosynthetic production of H2O2 in seawater. This catalyst exhibits high photocatalytic ability to produce H2O2 with the yield of 1776 μmol g−1h−1 (λ ≥ 420 nm; 34.8 mW cm−2) in real seawater, about 4.8 times higher than the pure polymer. Combining with in-situ photoelectrochemical and transient photovoltage analysis, the active site and the catalytic mechanism of this composite catalyst in seawater are also clearly clarified. This work opens up an avenue for a highly efficient and practical, available catalyst for H2O2 photoproduction in real seawater.

High overpotentials and low efficiency are two main factors that restrict the practical application for MoS 2 , the most promising candidate for hydrogen evolution catalysis. Here, RhMoS 2 nanocomposites, the addition of a small amount of Rh (5.2 wt%), exhibit the superior electrochemical hydrogen evolution performance with low overpotentials, small Tafel slope (24 mV dec −1 ), and long term of stability. Experimental results reveal that 5.2 wt% RhMoS 2 nanocomposite, even exceeding the commercial 20 wt% Pt/C when the potential is less than −0.18 V, exhibits an excellent mass activity of 13.87 A mg metal −1 at −0.25 V, four times as large as that of the commercial 20 wt% Pt/C catalyst. The hydrogen yield of 5.2 wt% RhMoS 2 nanocomposite is 26.3% larger than that of the commercial 20 wt% Pt/C at the potential of −0.25 V. The dramatically improved electrocatalytic performance of RhMoS 2 nanocomposites may be attributed to the hydrogen spillover from Rh to MoS 2 .broad range of applications. [24] The reason for these deficiencies may be due to the fact that MoS 2 has a relatively large Gibbs free energy (ΔG H ) of 0.08 eV. [23] There is a well-known volcano-type relation for HER catalysts, indicating that the optimal catalysts should exhibit a moderate Gibbs free energy for atomic hydrogen adsorption: [23,25] the catalysts with large ΔG H will fail to bind to hydrogen atoms and no evolution will take place; and the catalysts with small ΔG H will get blocked by hydrogen atoms and the subsequent hydrogen evolution becomes depressed. Therefore, MoS 2 needs to combine some materials with small ΔG H to fabricate composite catalysts, which may accelerate the rates of hydrogen adsorption and subsequent hydrogen evolution at different surfaces of catalysts, respectively. Ideally, the H adsorption takes place at a surface with small ΔG H ; while the hydrogen evolution occurs at a surface with large ΔG H . Such reasonably-designed composite catalysts might exhibit a high activity, even better than Pt catalyst.In this work, we employed noble metals and MoS 2 , as the strong H-adsorbed and quick H 2 -desorbed components respectively, to fabricate composite electrocatalysts (denoted as x wt% metal/MoS 2 , x means the relative mass ratio of noble metal in the composite) for HER. A systematical investigation was conducted for HER based on metal-MoS 2 nanocomposites by an in situ growth process.Among the investigated metal-MoS 2 nanocomposites, RhMoS 2 catalysts exhibit the most excellent HER activity. The optimal RhMoS 2 catalyst contains only 5.2 wt% Rh. Its Tafel slope (24 mV dec −1 ) is lower than that of the commercial 20 wt% Pt/C (30 mV dec −1 ); and its hydrogen product at −0.25 V is 26.3% larger than that of the Pt/C catalyst. The excellent HER performance of RhMoS 2 may be attributed to the hydrogen spillover from Rh to MoS 2 .

Room‐temperature phosphorescence (RTP)‐based sensors have distinctive advantages over the fluorescence counterparts, such as larger Stokes shifts and longer lifetimes. Unfortunately, almost all RTP sensors are operated on quenching‐based mechanisms given the sensitive nature of the emissive triplet state. Here we report a type of thioether RTP molecules that shows RTP “turn‐on” when volatile acid vapors such as HCl are in contact. To elucidate the underlying mechanism, model thioethers containing different donor/acceptor combinations are investigated via fluorescence spectroscopy and theoretical calculations aided by molecular coordinates obtained from single‐crystal X‐ray diffraction. It is revealed that a charge‐transfer character in the phosphorescence state is crucial. The “turn‐on” design concept may significantly broaden the sensing application scope for organic RTP molecules.