In the present work, NiFe layered double hydroxide (LDH) supported single Ru atoms in-situ growth on BiVO 4 photoanode (BiVO 4 @NiFe-LDHs/Ru) was fabricated to enhance the photoelectrochemical (PEC) water splitting. Ru atoms anchored to NiFe-LDHs via oxygen coordination to form Ru-O-M bonds, which induced electrons rearrangement to improve charge carriers separation and injection. Combining with the synergistic effect of Ru and NiFe-LDHs, BiVO 4 @NiFe-LDHs/Ru achieves high photocurrent density of 4.65 mA/cm 2 at 1.23 V vs. RHE. Besides, Ru atoms induced formation of V (5−x)+ to stabilize V atoms in the lattice of BiVO 4 , which avoided V 5+ dissolution during PEC water oxidation process. Density functional theory (DFT) calculation indicates that Ru SAs anchored to BiVO 4 @NiFe-LDHs decrease the reaction energy barrier of rate-limiting step (*O → *OOH), resulting in acceleration of OER process. This work provides an effective pathway to design high efficient and stable photoanodes with single atoms for feasible PEC water splitting application.
Molybdenum oxide (MoO 3− x , x < 3) has been successfully used as an efficient hole-selective contact material for crystalline silicon heterojunction solar cells. The carrier transport capability strongly depends on its work function, that is, oxygen vacancies; however, there are lack of effective methods to modulate the multiple oxidation states. Herein, the oxidation states of solution-processed MoO 3− x by doping Nb 5+ to improve its hole-selective contact performance with silicon are tuned. With the optimum doping concentration of 5%, both the reduced Mo 5+ and oxygen vacancies increase, resulting in a decrease in the contact resistivity between the MoO 3− x film and p -type silicon from 161.1 to 62.9 mΩ·cm 2 and an increase of the effective carrier lifetime from 165.4 to 391.0 μs simultaneously. Similarly, the doping of Ta 5+ or V 5+ in MoO 3− x improves the passivated contact performance with silicon, while the former increases the concentration of oxygen vacancies and the latter reduces it. The solar cell with the structure of Ag/MoO 3− x :Nb/ p -Si exhibits a conversion efficiency of 18.37%, which is the highest so far reported for the solution-processed MoO 3− x /silicon heterojunction. This work demonstrates a feasible strategy of tuning hole selectivity in MoO 3− x by doping for high-efficiency solar cells and other optoelectronic device applications.
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