performance and low price for working in alkaline solution.Ruthenium, as a member of platinumgroup metals with 1/30 price of Pt, [14] has been proved to be a promising catalyst for HER in alkaline solution due to its high efficiency on water dissociation, [15][16][17][18] however, the strong interaction between Ru and H atoms impedes the subsequent hydrogen evolution because of the well-known scaling relationship for heterogeneous catalysts. [17,[19][20][21] Many efforts had been devoted to constructing Rubased heterostructures (e.g., Ru/carbon quantum dots, [22] Ru/C 2 N, [18] RuCo/ nitrogen-doped graphene, [23] fcc-Ru/ C 3 N 4 /C, [17] Ru/nitrogen-doped carbon, [24] Ru/graphene [25] ), which show great advantages on promoting water dissociation by synergistic effect. Nevertheless, less attention was paid on the improvement of hydrogen adsorption. Recently, singleatom alloys (SAAs), which comprise separated solute atoms in metallic matrix, show great potential on circumventing scaling relationships. [23,26,27] meanwhile, the interaction between the solute atoms and matrix can modify their electronic structure, [26,28,29] leading to a suitable adsorption energy for hydrogen. Consequently, constructing Ru-based SAAs opens a new avenue toward high HER performance.Herein, we reported the synthesis of RuAu SAAs through a laser ablation in liquid (LAL) technique, which possesses strong quenching effect so as to fabricate metastable nanostructures with novel properties. [30,31] We choose Au as the alloying element on the basis of the following considerations: First, Au is known as an inert metal with weak hydrogen adsorption thus can counteract the strong hydrogen adsorption of Ru matrix. Second, the immiscibility between Au and Ru may create a unique geometric and electronic structure in RuAu SAAs. [32,33] Finally, chemically inert Au favors long-term durability during the reaction. As such, the as-prepared RuAu catalyst exhibits a low overpotential, 24 mV@10 mA cm −2 , which is much lower than Pt/C (46 mV@10 mA cm −2 ) in alkaline media. Moreover, the turnover frequency (TOF) of RuAu SAAs is three times that of the Pt/C catalyst. Density functional theory (DFT) computation reveals that the high performance originates from the relay catalysis of Ru host (for water dissociation) and Au dopant (for hydrogen evolution). To the best of our knowledge, this is the first report on the synthesis of RuAu SAAs with outstanding HER performance in alkaline media. Furthermore, the idea of the mixing immiscible metallic elements by LAL can be facilely Highly efficient and stable catalysts for the hydrogen evolution reaction, especially in alkaline conditions are crucial for the practical demands of electrochemical water splitting. Here, the synthesis of a novel RuAu single-atom alloy (SAA) by laser ablation in liquid is reported. The SAA exhibits a high stability and a low overpotential, 24 mV@10 mA cm −2 , which is much lower than that of a Pt/C catalyst (46 mV) in alkaline media. Moreover, the turnover frequency of RuAu SAA is th...
advantages, such as solution processability, low cost, and fl exibility. The invention of the bulk heterojunction (BHJ) architecture is regarded as a milestone in the history of OPV. [ 3,4 ] The BHJ architecture consists of nanoscale interpenetrating networks of donor and acceptor phases with phase separation close to the exciton diffusion length (≈10 nm). [ 5 ] The interfacial area between donor and acceptor materials is increased by several orders of magnitude compared to the bilayer architecture resulting in effi cient exciton separation, while also allowing devices thick enough to absorb a sizeable fraction of the solar spectrum. Based on this concept, OPV devices have already achieved effi ciencies of over 9% for single-junction cells. [ 6 ] The development of new polymers has been one of the most critical factors responsible for the realization of high efficiency organic solar cells. The effi ciency of polymer solar cells is related to the shortcircuit current density ( J sc ), open-circuit voltage ( V oc ), and fi ll factor (FF). The basic goal when designing a new polymer is to improve J sc and V oc simultaneously. Ideally, a polymer with low band gap and so a broader absorption spectrum is preferable, as this allows for conversion of more solar photons into electrons. The open-circuit voltage is related to the energy difference between the highest occupied molecular orbital (HOMO) level of the electron donor material and the lowest unoccupied molecular orbital (LUMO) level of the electron acceptor material, [7][8][9][10] depending more directly on the energy of the CT state. [ 11 ] Using a low bandgap donor polymer with LUMO level close to the LUMO of the acceptor is a promising way to improve both J sc and V oc . At the same time, it is necessary to maintain a minimum energy offset between the LUMO level of the donor polymer and the LUMO level of the fullerene acceptor in order to provide a suffi cient driving force for charge separation. [ 12 ] Among the various electron donor polymers employed to date, polymers based on benzo[1,2-b:4,5-b′]dithiophene (BDT) and thieno[3,4-b]thiophene (TT) units represent one of the most effi cient classes of electron donor polymers and have shown excellent device performance. [13][14][15][16] In order to tune the band gap and energy levels, much effort has been devoted to modifying the functional groups of the BDT and TT units. [ 14,15,[17][18][19] The modifi cation of side groups in particular has a signifi cant impact on electrochemical and optoelectronic properties. Through the addition of high electron affi nityThe microstructure of the polymer PBDTTT-EFT and blends with the fullerene derivative PC 71 BM that achieve solar conversion effi ciencies of over 9% is comprehensively investigated. A combination of synchrotron techniques are employed including surface-sensitive near-edge X-ray absorption fi ne structure (NEXAFS) spectroscopy and bulk-sensitive grazing-incidence wide angle X-ray scattering (GIWAXS). A preferential "face-on" orientation of PBDTTT-EFT is obse...
Laser ablation in liquid was used to prepare homogeneous copper−zinc alloy catalysts that exhibited excellent selectivity for C 2 H 4 in CO 2 electroreduction, with faradaic efficiency values as high as 33.3% at a potential of −1.1 V (vs reversible hydrogen electrode). The high proximity of Cu and Zn atoms on the surface of the catalyst was found to facilitate both stabilization of the CO* intermediate and its transfer from Zn atoms to their Cu neighbors, where further dimerization and protonation occur to give rise to a large amount of ethylene product. The new homogeneous nanocatalyst, along with the mechanism proposed for its performance, may be very helpful for in-depth understanding of processes related to carbon dioxide electroreduction and conversion.
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