Wei Jin,Liyuan Zhang,Wenjing Zhang,Qian Sun,Dekai Zhang,Hui Miao,Xiaoyun Hu
As a traditional n-type semiconductor, TiO2 has good UV absorption ability and stable physical and chemical properties. However, its wide band gap and low oxygen evolution reaction (OER) activity limit its application in the field of photoelectrochemical (PEC) water splitting. In this work, a type-II TiO2/CuNi2S4 heterojunction photoanode is successfully constructed, which expanded the light absorption range to visible and enhanced the OER activity. Firstly, TiO2 nanotubes (NTs) thin films are prepared on Ti substrates by two-step anodization, and then the bi-functional electrocatalytic material CuNi2S4 is grown on TiO2 NTs in the shape of nanosheets (NSs) in situ by solvothermal method. As a bi-functional electrocatalytic material, CuNi2S4 has good visible light absorption property as well as OER catalytic activity. Compared with TiO2, the IPCE value of TiO2/CuNi2S4 is 2.59% at 635 nm, and that of TiO2 is a mere 0.002%. The separation efficiency and injection efficiency increase from 2.49% and 31.52% to 3.61% and 87.77%, respectively. At 1.23 V vs. RHE, the maximum photocurrent density is 0.26 mA/cm2, which is 2.6 times than that of TiO2 (0.11 mA/cm2), and can be maintained at 0.25 mA/cm2 for at least 2 h under light illumination. Moreover, a hydrogen production rate of 4.21 μmol⋅cm−2⋅h−1 is achieved within 2 h. This work provides a new idea for the application of TiO2 in the field of PEC water splitting and the construction of efficient and stable photoelectronic devices.
The production of hydrogen via the photolysis of water represents a sustainable and environmentally benign approach to energy generation, which has the potential to mitigate energy shortages and environmental degradation. Nonetheless, the efficiency of photocatalysts is significantly limited by the effectiveness of charge carrier separation. Reducing the diffusion distance of these carriers can enhance their overall performance of the photocatalyst. In this context, a composite photocatalyst comprising CuNi 2 S 4 and ZnCdS was synthesized through one-step hydrothermal process. This bulk-phase heterojunction increases the nano-contact areas while maintaining an interface distance that is smaller than the diffusion distance of the carriers. Consequently, the optimal hydrogen production rate achieved was 33.87 mmol/g h, which is an order of magnitude greater than that of pure ZnCdS at 3.35 mmol/g h. Furthermore, the quantum efficiency at 400 nm reached 16 %. The photocurrent of the ZCS-CNS-3 % sample was 57.1 μA/cm², 4.35-fold of pure ZnCdS at 13.1 μA/cm². The incorporation of CuNi 2 S 4 significantly reduces the overpotential required for hydrogen evolution, while concurrently reducing the carrier transfer resistance by an order of magnitude. This bulk-phase structure not only broadens the prospects for the advancement of green and clean energy solutions but also enhances the methodologies for synthesizing nano-contact photocatalysts.
Xianfeng Sun,Yan Zhang,Cheng Du,Mingjiang Xie,Jian Chen,Liu Wan
The interface engineering strategy of hybridizing transition metal sulfides (TMSs) with other electroactive materials has proven to be a powerful strategy to exploit advanced electrode materials for supercapacitors (SCs). Herein, CuNi 2 S 4 nanospheres were grown directly onto carbon cloth (CC) by a single-step electrodeposition procedure, and the bimetallic selenide NiCoSe 2 then was deposited over the CuNi 2 S 4 nanospheres to create a flexible CuNi 2 S 4 @NiCoSe 2 hybrid electrode material with special core–shell architecture. The nanoflower-like hybrid structure not only increases the redox active sites but also provides short paths for electron/ion transport and improves redox reaction kinetics. The CuNi 2 S 4 @NiCoSe 2 electrode achieves a capacity value of 979.2 C g −1 /3.43 C cm −2 at 1 A g −1 along with good rate performance, outperforming pristine CuNi 2 S 4 and NiCoSe 2 . This wonderful supercapacitive behavior is related to the synergy of CuNi 2 S 4 ’s high conductivity and NiCoSe 2 ’s high electroactivity. Furthermore, the hybrid supercapacitor using the CuNi 2 S 4 @NiCoSe 2 cathode along with the porous carbon from pine pollen anode achieves an energy density (78.9 Wh kg −1 at 720.2 W kg −1 ) and maintains 91.4 % of original capacity after 50,000 cycles. These findings affirm that the CuNi 2 S 4 @NiCoSe 2 heterostructure is structurally superior as an electrode material in advanced energy storage systems.
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