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The significant challenge faced by Li–O 2 batteries (LOBs) lies in their slow oxygen reduction and evolution kinetics, which greatly necessitates the development of highly active catalysts. Herein, we report a high-performance oxygen cathode (RuCo-NC) that is achieved by uniformly dispersing the nanoalloy of noble metal Ru and transition metal Co on the three-dimensional (3D) nanoporous carbon. Density functional theory (DFT) calculations reveal a prominent electron transfer process between Ru and Co, along with a substantial abundance of electron transfer sites on RuCo-NC. These characteristics contribute to a strong positive equilibrium effect on the formation and decomposition of Li 2 O 2 , which is crucial for LOBs. Furthermore, the calculated Gibbs free energy change during the oxygen reduction and evolution processes indicates that RuCo-NC exhibits the smallest overpotential compared to single metal catalysts. As a result, this RuCo-NC cathode enables the resulting LOB with a larger discharge specific capacity, lower overpotential for efficient oxygen reduction and evolution, and excellent cycling stability. This work introduces an effective method for fabricating nanoalloy catalysts with enhanced efficiency, promising advancements in energy applications. • The highly dispersed RuCo nanoalloy uniformly dispersed on nanoporous carbon was prepared. • In-depth sights into the transfer process between Ru and Co, leading to high performance. • The RuCo-NC oxygen cathode shows high battery performance and cycle stability. [ABSTRACT FROM AUTHOR]

Quantum dot sensitized solar cells (QDSSCs) require special electrolytes, which are not always compatible with the requirements of dye sensitized solar cells. CdS and PbS quantum dot sensitized solar cells are able to show promising power conversion efficiencies in the presence of an organic thiolate/disulfide redox electrolyte. Also, an appreciable enhancement in performance is noticed when such devices are co-sensitized with a Ru-dye. The measured cell efficiencies of the CdS/dye and PbS/dye co-sensitized solar cells are 3.93% and 4.18%, respectively, which are higher than the sum of the corresponding individual QDSSCs and the dye sensitized solar cell (DSSCs). The enhancement seen with co-sensitization was investigated and explained by the fact that it suppressed back electron transfer processes in the cell, which was ascertained by electrochemical impedance spectroscopy (EIS) results. [ABSTRACT FROM AUTHOR]

Abstract: A novel Cu2S counter electrode (CE), which is prepared through simple electroplating method, is used to fabricate CdS quantum dot sensitized solar cells. The cells applying our novel CE show high power conversion efficiency in its class, reaching 2.6% under standard AM1.5 illumination, which is higher than those with Platinum CE (1.1%) and brass based Cu2S CE (1.85%). This is due to the novel CE showing superior photoelectrochemical performance and electrocatalytic property indicated by current density–voltage (J–V), the incident photon to current efficiency (IPCE) and the electrochemical impedance spectroscopy (EIS) curves. [Copyright &y& Elsevier]