Owing to the sluggish kinetics for water oxidation, severe surface charge recombination is a major energy loss that hinders efficient photoelectrochemical (PEC) water splitting. Herein, a simple process is developed for preparing a new type of low-cost iron-cobalt oxide (FeCoO x ) as an efficient co-catalyst to suppress the surface charge recombination on bismuth vanadate (BiVO 4 ) photoanodes. The new FeCoO x /BiVO 4 photoanode exhibits a high photocurrent density of 4.82 mA cm −2 at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G illumination, which corresponds to >100% increase compared to that of the pristine BiVO 4 photoanode. The photoanode also demonstrates a high charge separation efficiency of ≈90% with excellent stability of over 10 h, indicating the excellent catalytic performance of FeCoO x in the PEC process. Density functional theory calculations and experimental studies reveal that the incorporation of Fe into CoO x generates abundant oxygen vacancies and forms a p-n heterojunction with BiVO 4 , which effectively promotes the hole transport/trapping from the BiVO 4 photocatalyst and reduces the overpotential for oxygen evolution reaction (OER), resulting in remarkably increased photocurrent densities and durability. This work demonstrates a feasible process for depositing cheap FeCoO x as an excellent OER cocatalyst on photoanodes for PEC water splitting.

Despite a suitable bandgap of bismuth vanadate (BiVO4) for visible light absorption, most of the photogenerated holes in BiVO4 photoanodes are vanished before reaching the surfaces for oxygen evolution reaction due to the poor charge separation efficiency in the bulk. Herein, a new sulfur oxidation strategy is developed to prepare planar BiVO4 photoanodes with in situ formed oxygen vacancies, which increases the majority charge carrier density and photovoltage, leading to a record charge separation efficiency of 98.2% among the reported BiVO4 photoanodes. Upon loading NiFeOx as an oxygen evolution cocatalyst, a stable photocurrent density of 5.54 mA cm−2 is achieved at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5 G illumination. Remarkably, a dual‐photoanode configuration further enhances the photocurrent density up to 6.24 mA cm−2, achieving an excellent applied bias photon‐to‐current efficiency of 2.76%. This work demonstrates a simple thermal treatment approach to generate oxygen vacancies for the design of efficient planar photoanodes for solar hydrogen production.

Single‐atom catalysts, which can maximize the utility of metal atoms, and at the same time achieve high catalytic performance, have attracted great interest in research. In this present study, 11 transition metal atoms supported on a graphdiyne (GDY) monolayer (TM@GDY, where TM represents a transition metal from Sc to Zn and Pt) as electrocatalysts are investigated by means of first‐principle calculations. It is found that the supported single atom is very stable at the corner of the acetylenic ring. These features can help in the realization of uniformly distributed and well‐ordered single atoms on GDY. Few composites viz Sc@GDY, Ti@GDY, V@GDY, Fe@GDY, and Pt@GDY display high catalytic activity toward hydrogen evolution reaction (HER). Especially for Ti@GDY and V@GDY, both C and TM are active sites which are the best HER catalysts among the studied composites. Moreover, Pt@GDY and Ni@GDY composites can be promising bifunctional electrocatalysts for water splitting [0.01 and 0.46 V for HER and oxygen evolution reaction (OER)] and metal–air‐battery (0.29 and 0.40 V for OER and oxygen reduction reaction) catalysts, respectively. This work demonstrates that GDY is indeed a promising single‐atom support which can be considered for the design of high activity and inexpensive multifunctional electrocatalysts for practical catalytic applications.

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The development of low-dimensional (LD) supramolecular materials with multifunctional electrocatalytic properties has sparked the attention of the catalysis community. Herein, we report the synthesis of a new class of 0D−2D heterostructures composed of boron carbon nitride nanosheets (BCN NSs) and fullerene molecules (C 60 /F) that exhibit multifunctional electrocatalytic properties for the hydrogen evolution/oxidation reactions (HER/HOR) and the oxygen evolution/reduction reactions (OER/ORR). The electrocatalytic properties were studied with varying F:BCN weight ratios to optimize the intermolecular electron transfer (ET) from the BCN NSs to the electron-accepting C 60 molecules. The nanohybrid supramolecular material with 10 wt % F in BCN NSs (10% F/BCN) exhibited the largest Raman and C 1s binding energy shifts, which were associated with greater cooperativity interactions and enhanced ET processes at the F/BCN interface. This synergistic interfacial phenomenon resulted in highly active catalytic sites that markedly boosted electrocatalytic activity of the material. The 10% F/BCN showed the highest tetrafunctional catalytic performance, outperforming the OER catalytic activity of commercial RuO 2 catalysts with a η 10 of 390 mV and very competitive onset potential values of −0.042 and 0.92 V vs RHE for HER and ORR, respectively, and a current density value of 1.47 mA cm −2 at 0.1 V vs RHE with an ultralow ΔG H* value of −0.03 eV toward the HOR process. Additionally, the 10% F/BCN catalyst was also used as both cathode and anode in a water splitting device, delivering a cell potential of 1.61 V to reach a current density of 10 mA cm −2 .