Ultralow-voltage hydrogen production and simultaneous Rhodamine B beneficiation in neutral wastewater

Electrocatalytic water splitting for hydrogen production is hampered by the sluggish oxygen evolution reaction (OER) and large power consumption and replacing the OER with thermodynamically favourable reactions can improve the energy conversion efficiency. Since iron corrodes easily and even self-corrodes to form magnetic iron oxide species and generate corrosion currents, a novel strategy to integrate the hydrogen evolution reaction (HER) with waste Fe upgrading reaction (FUR) is proposed and demonstrated for energy-efficient hydrogen production in neutral media. The heterostructured MoSe2/MoO2 grown on carbon cloth (MSM/CC) shows superior HER performance to that of commercial Pt/C at high current densities. By replacing conventional OER with FUR, the potential required to afford the anodic current density of 10 mA cm−2 decreases by 95%. The HER/FUR overall reaction shows an ultralow voltage of 0.68 V for 10 mA cm−2 with a power equivalent of 2.69 kWh per m3 H2. Additionally, the Fe species formed at the anode extract the Rhodamine B (RhB) pollutant by flocculation and also produce nanosized magnetic powder and beneficiated RhB for value-adding applications. This work demonstrates both energy-saving hydrogen production and pollutant recycling without carbon emission by a single system and reveals a new direction to integrate hydrogen production with environmental recovery to achieve carbon neutrality

Highly Efficient Nondoped Green Organic Light-Emitting Diodes with Combination of High Photoluminescence and High Exciton Utilization

Photoluminescence (PL) efficiency and exciton utilization efficiency are two key parameters to harvest high-efficiency electroluminescence (EL) in organic light-emitting diodes (OLEDs). But it is not easy to simultaneously combine these two characteristics (high PL efficiency and high exciton utilization) into a fluorescent material. In this work, an efficient combination was achieved through two concepts of hybridized local and charge-transfer (CT) state (HLCT) and “hot exciton”, in which the former is responsible for high PL efficiency while the latter contributes to high exciton utilization. On the basis of a tiny chemical modification in TPA-BZP, a green-light donor–acceptor molecule, we designed and synthesized CzP-BZP with this efficeient combination of high PL efficiency of η_PL = 75% in the solid state and maximal exciton utilization efficiency up to 48% (especially, the internal quantum efficiency of η_IQE = 35% substantially exceed 25% of spin statistics limit) in OLED. The nondoped OLED of CzP-BZP exhibited an excellent performance: a green emission with a CIE coordinate of (0.34, 0.60), a maximum current efficiency of 23.99 cd A^–1, and a maximum external quantum efficiency (EQE, η_EQE) of 6.95%. This combined HLCT state and “hot exciton” strategy should be a practical way to design next-generation, low-cost, high-efficiency fluorescent OLED materials