Rational design of noble metal catalysts with the potential to leverage efficiency is vital for industrial applications. Such an ultimate atom-utilization efficiency can be achieved when all noble metal atoms exclusively contribute to catalysis. Here, we demonstrate the fabrication of wafer-size amorphous PtSex film on SiO2 substate via a low-temperature amorphizing strategy, which offers single-atom-layer Pt catalysts with high atom-utilization efficiency (~26 wt%). This amorphous PtSex (1.2

The photoelectrochemical (PEC) properties of a Cu(In,Ga)Se2 (CIGS) photocathode covered with reduced graphene oxide (rGO) as a catalyst binder for solar‐driven hydrogen evolution are reported. Chemically reduced rGO with various concentrations is deposited as an adhesive interlayer between CIGS/CdS and Pt. PEC characteristics of the CIGS/CdS/rGO/Pt are improved compared to the photocathode without rGO due to enhancement of charge transfer via efficient lateral distribution of photogenerated electrons by conductive rGO to the Pt. More importantly, the introduction of rGO to the CIGS photocathode significantly enhances the PEC stability; in the absence of rGO, a rapid loss of PEC stability is observed in 2.5 h, while the optimal rGO increases the PEC stability of the CIGS photocathode for more than 7 h. Chemical and structural characterizations show that the loss of the Pt catalyst is one of the main reasons for the lack of long‐term PEC stability; the introduction of rGO, which acts as a binder to the Pt catalysts by providing anchoring sites in the rGO, results in complete conservation of the Pt and hence much enhanced stability. Multiple functionality of rGO as an adhesive interlayer, an efficient charge transport layer, a diffusion barrier, and protection layer is demonstrated.

By introducing ZnS between Cu(In, Ga)(S,Se) 2 (CIGS) and the CdS, we greatly improved the photoelectrochemical (PEC) performance of the CIGS photocathode for hydrogen evolution. Chemical and structural analysis reveals that the enhanced performance is due to additional band bending driven by in-diffusion of Zn into the CIGS and suppression of nonradiative recombination. The improved onset potential of CIGS photocathode was exploited by building a tandem device with a perovskite absorber for bias-free water splitting. A PEC device with a solar-to-hydrogen conversion efficiency exceeding 9% (the highest among PEC cells including a CIGS photocathode) with a stable operation of 6.5 h is demonstrated.

Green plants convert sunlight into high-energy chemicals by coupling solar-driven water oxidation in the Z-schemea nd CO 2 fixation in the Calvin cycle. In this study,f ormate dehydrogenase from Clostridium ljungdahlii (ClFDH) is interfaced with a TiO 2 -coatedC uFeO 2 andC uO mixed (ClFDH-TiO 2 j CFO) electrode. In this biohybrid photocathode, the TiO 2 layer enhances the photoelectrochemical( PEC) stability of the labile CFO photocathode and facilitates the transfer of photoexcited electrons from the CFO to ClFDH.F urthermore, inspired by the natural photosynthetic scheme, the photobiocathode is combined with aw ater-oxidizing, FeOOH-coated BiVO 4 (FeOOH j BiVO 4 ) photoanode to assemble aw ireless Z-schemeb iocatalytic PEC device as as emi-artificial leaf. The leaf-like structure effects a bias-freeb iocatalytic CO 2 -to-formate conversion under visible light. Its rate of formate production is 2.45 times faster than that without ClFDH. Thisw ork is the first example of aw ireless solar-driven semi-biological PEC system for CO 2 reduction that uses water as an electron feedstock.

Although the performance of transparent conducting oxides based on bixbyite In(2)O(3) (Sn doped In(2)O(3): ITO) and wurtzite ZnO (Al, In, and Ga doped ZnO) is sufficient in conventional optoelectronic devices, their flexibility remains insufficient for demands in mobile and foldable electronics generation. A lot of alternative materials such as metallic nanowires and carbon based nano-structures have been tried for transparent flexible electrodes, but poor thermal stability of metal nanowires and limits in conductivity of carbon based nano-structures are still waiting for permanent solutions. Here, we show that the cross-linked ITO nano-branches have superior mechanical flexibility compared to ITO bulk film without any cracks even with a bending radius of 0.1 cm. Moreover, for equivalent sheet resistivity, the ITO nano-branches exhibit optical transmittance comparable to that of commercial metallic nanowires (such as Ag and Cu in the visible spectrum) but show far superior thermal stability in conductivity without any degradation even at a temperature of 200 °C and a humidity of 90%.

We report on the photoelectrochemical (PEC) performance and stability of Cu(In,Ga)Se (CIGS)-based photocathodes for photocatalytic hydrogen evolution from water. Various functional overlayers, such as CdS, TiO, ZnSnO, and a combination of the aforementioned, were applied on the CIGS to improve the performance and stability. We identified that the insertion of TiO overlayer on p-CIGS/n-buffer layers significantly improves the PEC performance. A multilayered photocathode consisting of CIGS/CdS/TiO/Pt exhibited the best current-potential characteristics among the tested photocathodes, which demonstrates a power-saved efficiency of 2.63%. However, repeated linear sweep voltammetry resulted in degradation of performance. In this regard, we focused on the PEC durability issues through in-depth chemical characterization that revealed the degradation was attributed to atomic redistribution of elements constituting the photocathode, namely, in-diffusion of Pt catalysts, out-diffusion of elements from the CIGS, and removal of the metal-oxide layers; the best-performing CIGS/CdS/TiO/Pt photocathode retained its initial performance until the TiO overlayer was removed. It was also found that the durability of CIGS photocathodes with a TiO-coated metal-oxide buffer layer such as ZnSnO was better than those with a TiO-coated CdS, and the degradation mechanism was different, suggesting that the stability of a CIGS-based photocathode can be improved by careful design of the structure.

The transmittance of Ag-based electrode increased through suppressing surface plasmons (SPs) coupling. When 10-nm-thick Ag was deposited on small-dielectric-constant (ε) film (LiF, SiO), SPs coupling was induced, resulting in low transmittance (<40%) in visible region. At the Ag/large-ε oxide interface (WO3 and MoO3), SPs were suppressed, and the film showed increased transmittance (∼80%). Organic light emitting diodes using Ag/WO3 (ε: 35) as a transparent electrode showed 1.26 times greater luminance and 32.6% greater power efficiency than using Ag/LiF (ε: 5). These results provide us with an important guideline for enhancing the transmittance of Ag/dielectric film by controlling SPs coupling.

Controlling the wavelength of electrodes within a desirable region is important in most optoelectronic devices for enhancing their efficiencies. Here, we investigated a full-color flexible transparent electrode using a wavelength matching layer (WML). The WMLs were able to adjust the optical-phase thickness of the entire electrode by controlling refractive indices and were capable of producing desirable colors in the visible band from 470 to 610 nm. Electrodes with tungsten oxide (WO(3)) having a refractive index of 1.9 showed high transmittance (T = 90.5%) at 460 nm and low sheet resistance (R(s) = 11.08 Ω/sq), comparable with those of indium tin oxide (ITO, T = 86.4%, R(s) = 12 Ω/sq). The optimum structure of electrodes determined by optical simulation based on the characteristic matrix method agrees well with that based on the experimental method. Replacing the ITO electrode with the WO(3) electrode, the luminance of blue organic light-emitting diodes (λ = 460 nm) at 222 mA/cm(2) increased from 7020 to 7200 cd/m(2).