Morphology Engineering of BiVO₄ with CoO_x Derived from Cobalt‐containing Polyoxometalate as Co‐catalyst for Oxygen Evolution

Abstract

Bismuth vanadate (BiVO 4 ) as a metal oxidation semiconductor has stimulated extensive attention in the photocatalytic water splitting field. However, the poor transport ability and easy recombination of charge carriers limit photocatalytic water oxidation activity of pure BiVO 4 . Herein, the photocatalytic activity of BiVO 4 is enhanced via adjusting its morphology and combination co-catalyst. First, the Cu-BiVO 4 was synthesized by copper doping to control the growth of {110} facet of BiVO 4 , which is regarded for the separation of photo-generated charge carriers. Then the CoO x in-situ generated from K 6 [SiCo II (H 2 O)W 11 O 39 ] • 16H 2 O was photo-deposited on Cu-BiVO 4 surface as co-catalyst to speed up reaction kinetics. Cu-BiVO 4 @CoO x hybrid catalyst shows highest photocatalytic activity and best stability among all the prepared catalysts. Oxygen evolution is about 34.6 μmol in pH 4 acetic acid buffer under 420 nm LED irradiation, which is nearly 20 times higher than that of pure BiVO 4 . Apparent quantum efficiency (AQE) in 1 h and O 2 yield are 1.83% and 23.1%, respectively. O 2 evolution amount nearly maintains the original value even after 5 cycles.

Prussian Blue Type Cocatalysts for Enhancing the Photocatalytic Water Oxidation Performance of BiVO4

“…The boosted amplitude of O 2 evolution rate for Co−Co PBA@BiVO 4 ‐10 compared to that of pure BiVO 4 is pretty high among those of reported BiVO 4 based PEC or photocatalytic systems for water oxidation (Table S1 and S2) [25–29,35–46] . O 2 production kinetic curve of Co−Co PBA@BiVO 4 ‐10 sample during 4 h displays that O 2 evolution amount always increases but rate gradually slows down (Figure 4c), which may be caused by the change of pH and decreased concentration of NaIO 3 .…”

“…[34] The boosted amplitude of O 2 evolution rate for CoÀ Co PBA@BiVO 4 -10 compared to that of pure BiVO 4 is pretty high among those of reported BiVO 4 based PEC or photocatalytic Chemistry-A European Journal systems for water oxidation (Table S1 and S2). [25][26][27][28][29][35][36][37][38][39][40][41][42][43][44][45][46] O 2 production kinetic curve of CoÀ Co PBA@BiVO 4 -10 sample during 4 h displays that O 2 evolution amount always increases but rate gradually slows down (Figure 4c), which may be caused by the change of pH and decreased concentration of NaIO 3 . As for pure BiVO 4 , the degree of the change in pH and concentration of NaIO 3 is smaller than those of the CoÀ Co PBA@BiVO 4 -10 sample due to the low photocatalytic activity, so the O 2 evolution rate has not changed too much.…”

Transition‐Metal‐Based Cocatalysts for Photocatalytic Water Splitting

“…Transition metal oxides involving the cobalt oxide, [ 48,355,356,358–361,363–365,381 ] manganese oxide, [ 49,366,381a,382 ] chromium oxide, [ 357,383 ] molybdenum oxide, [ 384 ] nickel oxide, [381a,382b] iron oxide, [ 362,381a ] copper oxide, [381a] lead oxide, [382b] and several bimetal oxides [ 367–370,385 ] have been investigated as active cocatalysts to collect photoinduced holes for O 2 production in photocatalytic water splitting. The deposition of these cocatalysts is usually achieved based on the impregnation, hydrothermal, and photodeposition methods.…”

“…Here, their recent advances would be discussed in detail. [355] Ta 3 N 5 CoO x Impregnation λ > 420 nm (Xe) AgNO 3 4000 (O 2 ) 11.3 (500-600 nm) 2 (2014) [356] Ba [357] CeO 2 CoO x Impregnation UV-cut off (Xe) AgNO 3 208.4 (O 2 ) --(2017) [358] CTPs CoO x Impregnation λ > 300 nm (Xe) AgNO 3 100 (O 2 ) --(2018) [48] Bi (2019) [359] BaTaO 2 N CoO x Impregnation λ > 420 nm (Xe) AgNO 3 3495 (O 2 ) 11.9 (420 nm) -(2019) [360] α-Fe [362] Linear conjugated organic polymer [363] BiVO 4 CoO x photodeposition 420 nm (LED) NaIO 3 230.8 (O 2 ) 1.83 15 (2021) [364] TaON CoO x photodeposition λ > 420 nm (Xe) AgNO 3 6120 AE 170 (O 2 ) 21.2 (420 nm) -(2021) [365] CdS/Ti 3þ -SrTiO (2021) [366] Ta 3 N 5 NiFeOx Solvothermal λ > 420 nm (Xe) Na 2 S 2 O 8 1320 (O 2 ) 24 (480nm) 15 (2016) [367] g-C 3 N 4 CoMn O Impregnation λ > 300 nm (Xe) AgNO 3 366 (O 2 ) 1 (380 nm) 7 (2018) [368] g-C 3 N 4 CoAl 2 O Reverse micelle λ > 420 nm (Xe) AgNO 3 1544 (O 2 ) 0.2 (420 nm) 45 (2020) [369] g-C 3 N 4 NiCo 2 O 4 Thermal treatment λ > 400 nm (Xe) AgNO 3 840 (O 2 ) 4.9 (380 nm) -(2020) [370] aza-CMP Co(OH) 2 Immersion λ > 420 nm (Xe) AgNO 3 572.8 (O 2 ) 1.48 (420 nm) -(2017) [371] g-C 3 N 4 Co(OH) 2 Immersion λ > 300 nm (Xe) AgNO 3 561.2 (O 2 ) 3.7 (380 nm) 24 (2019) [50] CeO 2 Fe(OH) 3 In situ growth (Xe) AgNO 3 357.2 (O 2 ) 24.67 20 (2021) [51] TiO 2 CoAl-LDH In situ growth λ > 200 nm (Xe) AgNO 3 2340 (O 2 ) --(2015) [372] g-C 3 N 4 NiCo-LDH Physical mixing λ > 300 nm (Xe) AgNO 3 537 (O 2 ) -10 (2017) [373] Co(OH) [53] PDI-Co α-FeOOH Hydrothermal λ > 420 nm (Xe) Water 27000 (O 2 ) 1.16 (500 nm) -(2020) [376] CdS FeOOH Precipitation λ > 420 nm (Xe) Na 2 S 2 O 8 676.50 (O 2 ) 4.6 (420 nm) 16 (2021) [52] BiVO 4 Co-Pi Photodeposition λ > 420 nm (Xe) NaIO 3 ---(2012) [27a] mpg-CNx Co-Pi Photodeposition λ > 400 nm (Xe) Na 2 S 2 O 8 1000 (O 2 ) -9 (2013) [377] TaON Co-Pi Photodeposition λ > 400 nm (Xe) AgNO 3 1750 (O 2 ) --(2015) [378] CdS Co-Pi Photodeposition λ ≥ 420 nm (Xe)...…”

Efficient Oxygen Evolution Reaction on Polyethylene Glycol‐Modified BiVO4 Photoanode by Speeding up Proton Transfer

“…DOI: 10.1002/smll.202201410 performance of pure BiVO 4 photoanode is far less than the theoretical value because of its inherent drawbacks, such as the recombination of charge in the bulk, the slow water oxidation kinetics at the photoanode/electrolyte interface. [12,13] To improve the separation efficiency, element doping, [14,15] morphology engineering, [16,17] heterostructure formation, [17,18] crystal facet control, [19,20] and plasmonic treatment [21,22] have been widely attempted.…”