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Developing an efficient bifunctional electrocatalyst for overall water splitting under all pH conditions is challenging. Iridium (Ir)-based materials are promising electrocatalysts, but the high cost and limited reserves of Ir restrict their widespread applications. Alloying Ir with 3d transition metals to produce ordered intermetallic compounds (IMCs) is a well-established strategy aimed at diminishing the reliance on Ir and enhancing electrocatalytic activity. In this work, we synthesize Ir3Ti IMCs on carbon nanotubes (i.e. Ir3Ti/CNT), which exhibit remarkable performances in both the HER and OER across a broad pH range. Specifically, Ir3Ti/CNT as both the anode and cathode delivers a current density of 10 mA cm−2 at low cell voltages of 1.51 V and 1.52 V in 0.5 M H2SO4 and 1.0 M KOH, respectively. The density functional theory (DFT) calculations further demonstrate that alloying Ir with Ti atoms establishes the electron-rich environment for Ir atoms and regulates the adsorption energy of reaction intermediates on the surface of Ir3Ti IMCs. Consequently, the energy barriers for overall water splitting are reduced and the electrocatalytic activities are improved. This study presents a compelling strategy for constructing advanced noble metal-based electrocatalysts with high efficiency, long-term stability, and pH-universality for overall water splitting. [ABSTRACT FROM AUTHOR]

The release of nanoparticles (NPs) to the environment poses an increasing potential threat to biological systems. This study investigated the phytotoxicity and accumulation of copper oxide (CuO) NPs to Elsholtzia splendens (a Cu-tolerant plant) under hydroponic conditions. The 50% effective concentration (EC50) of CuO NPs to E. splendens was about 480 mg/L, implying the tolerance of E. splendens to CuO NPs. The Cu content in the shoots treated with 1000 mg/L CuO NPs was much higher than those exposed to the comparable 0.5 mg/L soluble Cu and CuO bulk particles. CuO NPs-like deposits were found in the root cells and leaf cells. Cu K-edge X-ray absorption near-edge structure analysis further revealed that the accumulated Cu species existed predominantly as CuO NPs in the plant tissues. All these results suggested that CuO NPs can be absorbed by the roots and translocated to the shoots in E. splendens. [ABSTRACT FROM AUTHOR]