Abstract
As the development of oxygen evolution co-catalysts (OECs) is being actively undertaken, the tailored integration of those OECs with photoanodes is expected to be a plausible avenue for achieving highly efficient solar-assisted water splitting. Here, we demonstrate that a black phosphorene (BP) layer, inserted between the OEC and BiVO4 can improve the photoelectrochemical performance of pre-optimized OEC/BiVO4 (OEC: NiOOH, MnOx, and CoOOH) systems by 1.2∼1.6-fold, while the OEC overlayer, in turn, can suppress BP self-oxidation to achieve a high durability. A photocurrent density of 4.48 mA·cm−2 at 1.23 V vs reversible hydrogen electrode (RHE) is achieved by the NiOOH/BP/BiVO4 photoanode. It is found that the intrinsic p-type BP can boost hole extraction from BiVO4 and prolong holes trapping lifetime on BiVO4 surface. This work sheds light on the design of BP-based devices for application in solar to fuel conversion, and also suggests a promising nexus between semiconductor and electrocatalyst.
Highlights
As the development of oxygen evolution co-catalysts (OECs) is being actively undertaken, the tailored integration of those OECs with photoanodes is expected to be a plausible avenue for achieving highly efficient solar-assisted water splitting
Considering that the lateral size of black phosphorene (BP) is larger than the pore size of BiVO4 film, the depositing BP on BiVO4 photoanode was assisted by centrifuge-coated method (See experimental section for detail)
Compared to the morphology of the pure BiVO4 photoanode (Fig. 1b and Supplementary Fig. 5a), the SEM image of BP/BiVO4 does not reveal the presence of BP nanosheets on surface of BiVO4 photoanode (Fig. 1c and Supplementary Fig. 5b), which is in stark contrast to that the BiVO4 photoanode is immersed into the BP dispersion by natural adsorption or deposition (Supplementary Fig. 6)
Summary
As the development of oxygen evolution co-catalysts (OECs) is being actively undertaken, the tailored integration of those OECs with photoanodes is expected to be a plausible avenue for achieving highly efficient solar-assisted water splitting. Heteroatom doping[5,6,7], component or structural tuning[8,9,10], and loading of oxygen evolution co-catalysts (OECs)[11,12,13,14] are identified as the most promising approaches for overcoming these drawbacks and improving the PEC performance of BiVO4 photoanodes Among these methods, OEC loading can strongly suppress surface recombination in BiVO4 photoanodes and shift the photocurrent onset potential close to its flat-band potential for water oxidation, which is the most significant feature for achieving unbiased solar water splitting[15,16]. Kim and Choi demonstrated that the incorporation of a FeOOH compound can accelerate hole transport from BiVO4 to the NiOOH OEC because the hole transport resistance of FeOOH is lower than that of NiOOH13
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