RuO2 is one of the most important electrocatalyst materials as a key component of dimensionally stable anode (DSA) for chlorine evolution reaction, because of the high catalytic activity, while anodic corrosion remains a fundamental challenge that must be addressed. Here, we demonstrate that low-temperature annealing of RuO2 nanoparticles (∼1.7 nm) supported on Nb-doped TiO2 leads to the formation of durable active sites with superior activity and product selectivity toward active chlorine generation (10 mA cm–2 at 22 mV overpotential with a Faradaic efficiency of 97.3% in 0.6 M NaCl, which is much better than that of commercial DSA). The Nb doping not only enhances the electronic conductivity of TiO2 support, but also enables thermal diffusion of Ti atoms into the RuO2 lattice at only 200 °C, forming ultrafine solid-solution nanoparticles with ultrathin TiO2 surface as a protective layer. This work provides a cost-effective fabrication strategy of stable RuO2 electrocatalysts for anodic reactions, as well as additional insights into the design principle of DSA.

Cu 2 ZnSn(S,Se) 4 (CZTSSe) has generated considerable research interest owing to its composition of abundant elements and excellent light-absorption properties. However, CZTSSe thin-film solar cells suffer from a considerable deficit in the open-circuit voltage (V OC ), which is mainly due to the severe interfacial recombination induced by the rough surface of CZTSSe and numerous physical defects. In this study, to improve the morphology and reduce the interfacial recombination, an In 2 S 3 passivation layer was introduced between the CZTSSe and CdS layers via a chemical bath deposition process, and the effects of the In 2 S 3 layer on the device performance were systematically examined by performing various electrodynamic analyses. The CZTSSe solar cells with thin In 2 S 3 layers exhibited impressive increases in V OC and conversion efficiency (from 7.33 to 9.24 %), due to the suppression of physical defects and the refined surface morphology resulting from filling the voids and pinholes. In addition, the nanoscale roughness of the In 2 S 3 /CZTSSe surface increased the number of nucleation sites for the CdS nuclei, which may reduce the activation energy of the heterogeneous nucleation. The presence of In 2 S 3 layer resulted in uniform growth of CdS without macroscopic CdS agglomerates (i. e., reduced roughness of full devices), which improved the quality of the interface. These findings confirmed that the reduction of physical defects and the improved deposition of the CdS layer enabled by the added In 2 S 3 passivation layer improved the device performance.

efficiency (PCE) of OPVs has already reached 14.2%. [1] However, a major drawback for the commercialization of OPVs is their long-term stability under continuous operation. Especially, OPVs suffer from a rapid decrease in PCE during initial device operation, which is known as the "burn-in loss." [2][3][4][5][6] The origin of the burn-in loss is thought to be mainly related to the instability of the bulk heterojunction (BHJ) morphology and/or interface rather than the photo-oxidation of the photoactive layer.Morphological instability of photoactive layer is one of critical issues of burn-in loss in OPV. [7][8][9][10][11] Because electron-donating and electron-accepting materials are blended in a photoactive layer to form metastable BHJ, applying high-temperature heat or strong light can cause microscopic morphology changes resulting in the burn-in loss. [8,9] For typical OPVs utilizing a BHJ, a photoactive layer (blend of electrondonating conjugated polymer and electron-accepting fullerene) is sandwiched between two electrodes (anode/cathode) with their corresponding charge-transporting (hole/electron) interlayers. [12] The interlayers minimize the energy barrier between the photoactive layer and electrodes, and thereby enhance the collection efficiencies of electrons/holes on the cathode/ anode. Thus, significant efforts have been made to develop various electron-transporting layer (ETL) materials for OPVs such as transition metal oxides, [13] carbon-based materials, [14] polymers, [15] low work function metal salts, [16] and organicinorganic hybrids. [17] Among various ETL materials, transition metal oxides are commonly utilized because of their adequate highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, stability, transparency, and excellent electron mobility. [5,18] Additionally, transition metal oxide ETLs provide an excellent barrier property against oxygen and metal electrode diffusion compared to organic ETL materials. Various types of transition metal oxides such as zinc oxide (ZnO), [19] titanium oxide (TiO 2 or TiO x ), [20][21][22] tin oxide (SnO 2 or SnO x ), [23] and niobium oxide (Nb 2 O 5 or NbO x ) [24] have been explored for use as ETL materials for OPVs. Generally, the transition metal oxide layer is deposited by vacuum deposition techniques such as sputtering, [22] atomic layer deposition, [25] or It is revealed that instability of interface between photoactive layer and electron-transporting layer (ETL) is one of the causes of the rapid degradation of organic photovoltaics (OPV) performance during initial operation (burn-in loss) under the light soaking. The stability of OPV is greatly enhanced by applying a robust ETL composed of TiO 2 nanoparticles (TNPs). The TNPs bound with π-π interactive 3-phenylpentane-2,4-dione (TNP-Ph) form more robust ETLs than those bound with van der Waals interactive 3-methyl-2,4pentanedione TNP (TNP-Me). The OPV with TNP-Ph maintains 73% of its initial power conversion efficiency (PCE) after 1000 h of light soa...

Nanoporous photoelectrodes with photoactive semiconductors have been investigated for various energy applications such as solar cells and photoelectrochemical cells, but the deposition of the semiconducting materials on the nanoporous electrodes has been very challenging due to pore clogging or complete pore filling. Here, we propose a band alignment model that explains the morphology of the electrochemically deposited semiconductor layer on the semiconducting nanoporous oxide electrode. Briefly, the coating material with a conduction band edge higher (i.e., more negative) than that of the electrode material forms a conformal coating, which maintains the initial nanoporous structure. As a result, a conformal CdSe layer can be electrodeposited onto TiO2 nanotubes, which can be used as a photoelectrode of a sensitized solar cell. The electron dynamics studies revealed that the CdSe-sensitized TiO2 nanotube electrode exhibited faster charge transport and slower charge recombination than its dye-sensitized counterpart, which has been ascribed to the passivation of surface traps and the physically blocked back-electron transfer by the CdSe layer as well as the higher conduction band of CdSe.