Copper selenide (Cu3Se2 and Cu2-xSe) thin films: electrochemical deposition and electrocatalytic application in quantum dot-sensitized solar cells

Microwave-assisted hydrothermal synthesis of copper selenides (Cu2-xSe) thin films for quantum dots-sensitized solar cells

In this work, copper selenide (Cu_2-xSe) thin films were grown on FTO conductive glass substrates using a facile microwave-assisted hydrothermal method. The effects of synthesis parameters such as precursor components and deposition time on the stoichiometry and morphology of the synthesized films were systematically investigated through different techniques including XRD, SEM, and AFM. In order to evaluate the electrochemical catalytic performance of the synthesized copper selenide in electrolyte containing the sulfide/polysulfide redox couple, we assembled liquid-junction quantum dots-sensitized solar cells (QDSSC) using the synthesized copper selenide thin films as counter electrodes and CdSe quantum dots-sensitized mesoporous TiO₂as photoanodes. Under the illumination of one Sun (100 mW cm^-2), the QDSSC assembled with the optimal copper selenide CEs (Cu:Se = 1:1) exhibited a power conversion efficiency of 2.07%, which is much higher than that of traditional Pt counter electrode (0.76%).

Crystalline Copper Selenide as a Reliable Non-Noble Electro(pre)catalyst for Overall Water Splitting

Electrochemical water splitting remains a frontier research topic in the quest to develop artificial photosynthetic systems by using noble metal-free and sustainable catalysts. Herein, a highly crystalline CuSe has been employed as active electrodes for overall water splitting (OWS) in alkaline media. The pure-phase klockmannite CuSe deposited on highly conducting nickel foam (NF) electrodes by electrophoretic deposition (EPD) displayed an overpotential of merely 297 mV for the reaction of oxygen evolution (OER) at a current density of 10 mA cm-2 whereas an overpotential of 162 mV was attained for the hydrogen evolution reaction (HER) at the same current density, superseding the Cu-based as well as the state-of-the-art RuO2 and IrO2 catalysts. The bifunctional behavior of the catalyst has successfully been utilized to fabricate an overall water-splitting device, which exhibits a low cell voltage (1.68 V) with long-term stability. Post-catalytic analyses of the catalyst by ex-situ microscopic, spectroscopic, and analytical methods confirm that under both OER and HER conditions, the crystalline and conductive CuSe behaves as an electro(pre)catalyst forming a highly reactive in situ crystalline Cu(OH)2 overlayer (electro(post)catalyst), which facilitates oxygen (O2 ) evolution, and an amorphous Cu(OH)2 /CuOx active surface for hydrogen (H2 ) evolution. The present study demonstrates a distinct approach to produce highly active copper-based catalysts starting from copper chalcogenides and could be used as a basis to enhance the performance in durable bifunctional overall water splitting.

A Low-Temperature Molecular Precursor Approach to Copper-Based Nano-Sized Digenite Mineral for Efficient Electrocatalytic Oxygen Evolution Reaction

In the urge of designing noble metal-free and sustainable electrocatalysts for oxygen evolution reaction (OER), herein, a mineral Digenite Cu9 S5 has been prepared from a molecular copper(I) precursor, [{(PyHS)2 CuI (PyHS)}2 ](OTf)2 (1), and utilized as an anode material in electrocatalytic OER for the first time. A hot injection of 1 yielded a pure phase and highly crystalline Cu9 S5 , which was then electrophoretically deposited (EPD) on a highly conducting nickel foam (NF) substrate. When assessed as an electrode for OER, the Cu9 S5 /NF displayed an overpotential of merely 298±3 mV at a current density of 10 mA cm-2 in alkaline media. The overpotential recorded here supersedes the value obtained for the best reported Cu-based as well as the benchmark precious-metal-based RuO2 and IrO2 electrocatalysts. In addition, the choronoamperometric OER indicated the superior stability of Cu9 S5 /NF, rendering its suitability as the sustainable anode material for practical feasibility. The excellent catalytic activity of Cu9 S5 can be attributed to the formation of a crystalline CuO overlayer on the conductive Cu9 S5 that behaves as active species to facilitate OER. This study delivers a distinct molecular precursor approach to produce highly active copper-based catalysts that could be used as an efficient and durable OER electro(pre)catalysts relying on non-precious metals.

Construction of Sb2Se3 nanocrystals on Cu2−xSe@C nanosheets for high performance lithium storage

Cu_2−xSe@C@Sb₂Se₃ with enhanced electrochemical performance was designed and fabricated, where Sb₂Se₃ nanoparticles were anchored on Cu_2−xSe@C nanosheets.