Organic-inorganic hybrid-photoanode built from NiFe-MOF and TiO2 for efficient PEC water splitting

• Published in: Electrochimica acta Vol. 349; p. 136383
• Main Authors: Cui, Weicheng, Bai, Hongye, Shang, Jianpeng, Wang, Fagen, Xu, Dongbo, Ding, Jinrui, Fan, Weiqiang, Shi, Weidong
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.07.2020; Elsevier BV
• Subjects: Charge efficiency; Charge injection; Efficiency; Hybrid systems; Hybrid-photoanode; Hydroxides; Intermetallic compounds; Iron compounds; Metal-organic frameworks; Nickel compounds; NiFe-MOF; Oxidation; Photoanodes; Photoelectric effect; Photoelectric emission; Titanium dioxide; Unsaturated metal sites; Water splitting; Water splitting; Hybrid-photoanode; NiFe-MOF; Unsaturated metal sites
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2020.136383

Constructing the high-performance photoanode is critical to improve photoelectrochemical (PEC) efficiency, but it is still an inevitable challenge to rationally fabricate the organic-inorganic hybrid-photoanode system. For the first time, we report a novel hybrid-photoanode built from ultrathin NiFe-MOF and TiO2 by a sacrifice template method. The in-situ etch of NiFe-layered double hydroxide (LDH) on the surface of TiO2 has been successfully realized in the coordination environment, for creating coordinately unsaturated metal sites on NiFe-MOF. The coordinately unsaturated metal sites could significantly promote the water oxidation kinetic, compared with conventional electrode/electrolyte interface. The photocurrent density of the NiFe-MOF/TiO2 has reached about 3.35 times of bare TiO2 at 1.23 V (vs. RHE), and the incident photon to current conversion efficiency (IPCE) value has been improved up to 42% (at 390 nm). The significant augment of the charge injection (ηinjection) of 92.8% and charge separation (ηseparation) efficiency of 37.4% has also been exhibited. Moreover, NiFe-MOF/TiO2 shows a long-term stability ( < 10% decay) after 4 h of continuous illumination. This work provided a novel and rational strategy about the integration of the inorganic semiconductor and organic MOF, which can provide a new insight into understanding MOF-based catalysts for PEC water splitting. NiFe-MOF nanosheets were in-situ loaded on the surface of TiO2 to boost photoelectrochemical water splitting for the first time. The NiFe-MOF/TiO2 as a desirable hybrid-photoanode will benefit for in-depth understanding the behavior of organic-inorganic system on the solar energy conversion. [Display omitted] •NiFe-MOF plays an important role in the PEC performance of TiO2 photoanode.•Ni and Fe sites synergistically facilitate the water oxidation kinetics.•Ultra-thin structure of NiFe-MOF helps to improve the charge transfer rate.•The favorable stability endows NiFe-MOF/TiO2 with great potential in the future.