Efficient Charge Transfers in Highly Conductive Copper Selenide Quantum Dot-Confined Catalysts for Robust Oxygen Evolution Reaction

Abstract

Defective quantum dots (QDs) are the emerging materials for catalysis by virtue of their atomic-scale size, high monodispersity, and ultra-high specific surface area. However, the dispersed nature of QDs fundamentally prohibits the efficient charge transfer in various catalytic processes. Here, we report efficient and robust electrocatalytic oxygen evolution based on defective and highly conductive copper selenide (CuSe) QDs confined in an amorphous carbon matrix with good uniformity (average diameter 4.25 nm) and a high areal density (1.8 × 1012 cm–2). The CuSe QD-confined catalysts with abundant selenide vacancies were prepared by using a pulsed laser deposition system benefitted by high substrate temperature and ultrahigh vacuum growth conditions, as evidenced by electron paramagnetic resonance characterizations. An ultra-low charge transfer resistance (about 7 Ω) determined by electrochemical impedance spectroscopy measurement indicates the efficient charge transfer of CuSe quantum-confined catalysts, which is guaranteed by its high conductivity (with a low resistivity of 2.33 μΩ·m), as revealed by electrical transport measurements. Our work provides a universal design scheme of the dispersed QD-based composite catalysts and demonstrates the CuSe QD-confined catalysts as an efficient and robust electrocatalyst for oxygen evolution reaction.

The impact of Ni and Zn doping on the thermal durability and thermoelectric variables of pristine CuSe nanoparticles

“…42,43 The XPS profiles of Se 2d for all samples exhibit two photoelectron bands with binding energy values of 54.2 eV and 55.0 eV, designated as Se 2d 5/2 and Se 2d 3/2 , respectively, known as standard peaks of Se. 2–42,44 The identical patterns of both of the Cu 2p peaks and Se 3d peaks for each nanoparticle indicate the existence of CuSe.…”

“…The importance of copper selenides within the TMC family lies in their diverse range of applications, including thermoelectric devices, photovoltaics, energy storage, catalysis, and optoelectronics. 8–10 Copper selenides comprise a varied subgroup of p-type semiconductors that exist in a wide variety of stoichiometric phases, such as CuSe, 11 Cu 2 Se, CuSe 2 , 12 Cu 3 Se 2 , 13 Cu 5 Se 4 , 14 and Cu 7 Se 4 , 15 as well as non-stoichiometric forms of Cu 2− x Se (2.00 ≥ 2 − x ≥ 1.72). 16…”

Advanced electron paramagnetic resonance in chemical energy conversion: current status and future potential

“…Zinc vacancies (ZVs) are another cation vacancy, observed in a number of catalysts of the energy conversion field, i.e., ZnO, ZnS, ZnIn 2 S 4 , Zn 3 In 2 S 6 , Ni 12 P 5 / ZnIn 2 S 4 and ZnO/NiS@NiO/rGO. 139,[144][145][146][147] The EPR signal of ZVs is usually observed at g = 2.003 and in crystalline ZnS its g tensor has been resolved. 148 Thus far EPR has mainly been used to examine ZV generation in heterojunction catalysts, which is beneficial as this can improve the heterojunction's ability to form a charge separated state.…”

“…A few examples include the following: (i) monitoring the thermal treatment of ReSe 2 in an Ar atmosphere which initially introduced SeVs that were subsequently removed through Mo doping to form Re 1− x Mo x Se 2 ; for 0.4 < x < 1 the SeV was not detected; 136 (ii) monitoring calcination temperatures for CoSe 2 where it was seen that high temperature (160 °C to 180 °C) eliminated all SeVs; 138 (iii) monitoring the pulsed laser deposition method to introduce SeVs in CuSe. To be sure of the SeV, the EPR spectrum was omitted after catalyst annealing in the selenium atmosphere; 139 and finally, (iv) monitoring Ag doping of CdSe quantum dots (QD). Initially, Ag doping led to a large number of SeVs, which subsequently dropped at high doping levels.…”

Suppressed charge recombination via defect engineering of confined semiconducting quantum dots for photoelectrocatalysis

“…Here, in terms of the two aforementioned sides of photogenerated charge recombination and transfer, we successfully synthesized defect-engineered semiconducting CuSe QDs confined in a conductive amorphous carbon matrix via the pulsed laser deposition (PLD) technique with in situ vacuum annealing that we have recently developed. 19 Due to high substrate temperature and ultrahigh vacuum conditions of the PLD deposition, the Cu-Se bonds are destroyed by thermal energy, and the Se atoms are emitted due to their volatility, resulting in abundant Se vacancies generated in CuSe semiconducting QDs and the self-doping effect.…”