New Iron‐Cobalt Oxide Catalysts Promoting BiVO4 Films for Photoelectrochemical Water Splitting

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 (BiVO₄) photoanodes. The new FeCoO_x/BiVO₄ 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 BiVO₄ 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 BiVO₄, which effectively promotes the hole transport/trapping from the BiVO₄ 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.     

Bias-Free Solar Water Splitting by Tetragonal Zircon BiVO4 Nanocrystal Photocathode and Monoclinic Scheelite BiVO4 Nanoporous Photoanode

p-type tetragonal zircon BiVO₄ nanocrystal photocathodes (P-BVO) and n-type monoclinic scheelite BiVO₄ nanoporous photoanodes (N-BVO) are prepared by a hydrothermal method and an electrochemical synthesis method, respectively. Pt nanoparticles and cobalt-phosphate (Co-Pi) as co-catalysts are loaded by an electrodeposition way to improve the photoelectrochemical (PEC) performance of BiVO₄ (BVO) electrodes. After modification, a monochromatic incident photon-to-current conversion efficiency (IPCE) of P-BVO/Pt at 360 nm is improved by 2.2 times, and the highest IPCE of N-BVO/Co-Pi at 440 nm is increased by 1.7 times. The calculated electron-hole separation yield and the charge carrier injection yield of N-BVO/Co-Pi at 1.23 V_RHE are further improved to 80% and 86%, respectively. The surface modification also results in the latest ≈0.2% half-cell solar-to-hydrogen energy conversion efficiency (HC-STH) for a P-BVO/Pt photocathode and a higher ≈1.16% half-cell applied bias photon-to-current conversion efficiency (ABPE) for an N-BVO/Co-Pi photoanode. Furthermore, the prepared photoelectrodes are proved to have excellent stability for water splitting. Above all, a tandem-type PEC cell containing the newly developed P-BVO/Pt photocathode and an N-BVO/Co-Pi photoanode is built for the first time, which evolves H₂ and O₂ at a stoichiometric ratio of 2:1 with a bias-free STH of 0.14%.     

Amorphous Cobalt–Iron Hydroxide Nanosheet Electrocatalyst for Efficient Electrochemical and Photo‐Electrochemical Oxygen Evolution

Finding efficient electrocatalysts for oxygen evolution reaction (OER) that can be effectively integrated with semiconductors is significantly challenging for solar‐driven photo‐electrochemical (PEC) water splitting. Herein, amorphous cobalt–iron hydroxide (CoFe? H) nanosheets are synthesized by facile electrodeposition as an efficient catalyst for both electrochemical and PEC water oxidation. As a result of the high electrochemically active surface area and the amorphous nature, the optimized amorphous CoFe? H nanosheets exhibit superior OER catalytic activity in alkaline environment with a small overpotential (280 mV) to achieve significant oxygen evolution (j = 10 mA cm^?2) and a low Tafel slope (28 mV dec^?1). Furthermore, CoFe? H nanosheets are simply integrated with BiVO₄ semiconductor to construct CoFe? H/BiVO₄ photoanodes that exhibit a significantly enhanced photocurrent density of 2.48 mA cm^?2 (at 1.23 V vs reversible hydrogen electrode (RHE)) and a much lower onset potential of 0.23 V (vs RHE) for PEC‐OER. Careful electrochemical and optical studies reveal that the improved OER kinetics and high‐quality interface at the CoFe? H/BiVO₄ junction, as well as the excellent optical transparency of CoFe? H nanosheets, contribute to the high PEC performance. This study establishes amorphous CoFe? H nanosheets as a highly competitive candidate for electrochemical and PEC water oxidation and provides general guidelines for designing efficient PEC systems.     

Photoinduced Absorption Spectroscopy of CoPi on BiVO4: The Function of CoPi during Water Oxidation

This paper employs photoinduced absorption and electrochemical techniques to analyze the charge carrier dynamics that drive photoelectrochemical water oxidation on bismuth vanadate (BiVO₄), both with and without cobalt phosphate (CoPi) co‐catalyst. These results are correlated with spectroelectrochemical measurements of Co^II oxidation to Co^III in a CoPi/FTO (fluorine doped tin oxide) electrode during dark electrocatalytic water oxidation. Electrocatalytic water oxidation exhibits a non‐linear dependence on Co^III density, with a sharp onset at 1 × 10¹⁷ Co^III cm^?2. These results are compared quantitatively with the degree of CoPi oxidation observed under conditions of photoinduced water oxidation on CoPi–BiVO₄ photoanodes. For the CoPi–BiVO₄ photoanodes studied herein, ≤5% of water oxidation proceeds from CoPi sites, making the BiVO₄ surface the predominant water oxidation site. This study highlights two key factors that limit the ability of CoPi to improve the catalytic performance of BiVO₄: 1) the kinetics of hole transfer from the BiVO₄ to the CoPi layer are too slow to effectively compete with direct water oxidation from BiVO₄; 2) the slow water oxidation kinetics of CoPi result in a large accumulation of Co^III states, causing an increase in recombination. Addressing these factors will be essential for improving the performance of CoPi on photoanodes for solar‐driven water oxidation.     

Improvement of BiVO4 Photoanode Performance During Water Photo‐Oxidation Using Rh‐Doped SrTiO3 Perovskite as a Co‐Catalyst

In this work, a water splitting photoanode composed of a BiVO₄ thin film surface modified by the deposition of a rhodium (Rh)‐doped SrTiO₃ perovskite is fabricated, and the Rh‐doped SrTiO₃ outer layer exhibits special photoelectrochemical (PEC) oxygen evolution co‐catalytic activity. Controlled intensity modulated photo‐current spectroscopy, electrochemical impedance spectroscopy, and other electrochemical results indicate that the Rh on the perovskite provide an oxidation active site during the PEC water oxidation process by reducing the reaction energy barrier for water oxidation. Theoretical calculations indicate that the water oxidation reaction is more likely to occur on the (110) crystal plane of Rh‐SrTiO₃ because the oxygen evolution reaction overpotential on the (110) crystal plane is reduced significantly. Therefore, the obtained BiVO₄/Rh5%‐SrTiO₃ photoanode exhibits an optimized PEC performance. In particular, it facilitates the saturation of the photocurrent density. Thus, the presence of doped Rh in SrTiO₃ can reduce the amount of noble metals required while achieving excellent and stable oxygen evolution properties.     

Metal–Organic Framework Derived Narrow Bandgap Cobalt Carbide Sensitized Titanium Dioxide Nanocage for Superior Photo‐Electrochemical Water Oxidation Performance

Despite recent progress in photo‐electrochemical (PEC) water oxidation systems for TiO₂‐based photoanodes, PEC performance improvement is still seriously hampered due to poor carrier transport efficiency and sluggish surface water oxidation kinetics of pristine TiO₂. Herein, for the first time a brand new metal–organic framework (MOF)‐derived Co₃C nanosheet with narrow bandgap energy is demonstrated, to effectively sensitize TiO₂ hollow cages as a heterostructure photoanode for PEC water oxidation. It is found that MOF‐derived Co₃C nanosheet with narrow bandgap characteristic can simultaneously accelerate the surface water oxidation kinetics and extend the light harvesting range of pristine TiO₂. Meanwhile, a uniquely matched type‐II heterojunction constructed between MOF‐derived Co₃C and TiO₂ results in an evidently spontaneous e^?/h⁺ separation. MOF‐derived Co₃C/TiO₂ heterostructure photoanodes bring about drastically improved PEC water oxidation performance. Specifically, MOF‐derived Co₃C‐3/TiO₂ photoanode with an optimized content of Co₃C achieves the highest photocurrent density and charge separation efficiency of 2.6 mA cm^?2 and 92.6% at 1.23 V versus reversible hydrogen electrode, corresponding to 201% and 152% improvement compared with pristine TiO₂ nanocages. The ingeniously prepared MOF‐derived Co₃C carbide with narrow bandgap energy as a cocatalyst paves new way to construct potentially high performance solar‐energy conversion system.     

Analysis of Optical Losses in a Photoelectrochemical Cell: A Tool for Precise Absorptance Estimation

Optical losses in a photoelectrochemical (PEC) cell account for a substantial part of solar‐to‐hydrogen conversion losses, but limited attention is paid to the detailed investigation of optical losses in PEC cells. In this work, an optical model of combined coherent and incoherent light propagation in all layers of the PEC cell based on spectroscopic measurements is presented. Specifically, photoelectrodes using transparent conductive substrates such as F:SnO₂ coated with thin absorber films are focused. The optical model is verified for hematite photoanodes fabricated by atomic layer deposition and successfully used to determine wavelength‐dependent reflection, transmission, layer absorptances, and charge generation rates. Furthermore, the calculated absorptances enable 20–30% more accurate calculations of the absorbed photon‐to‐current efficiency of PEC cells. Our optical model is a powerful tool for the optimization of the optical performance of PEC cells focusing on single absorber or tandem configurations and represents a cornerstone of a complete (optical and electrical) model for PEC water splitting cells.     

Modular Layer‐by‐Layer Assembly of Polyelectrolytes,Nanoparticles, and Molecular Catalysts into Solar‐to‐Chemical Energy Conversion Devices

The design and fabrication of solar‐to‐chemical energy conversion devices are enabled through interweaving multiple components with various morphologies and unique functions using a versatile layer‐by‐layer assembly method. Cationic and anionic polyelectrolytes are used as an electrostatic adhesive to assemble the following functional materials: plasmonic Ag nanoparticles for improved light harvesting, upconversion nanoparticles for utilization of near‐infrared light, and polyoxometalate water oxidation catalysts for enhanced catalytic activity. Polyelectrolytes also have an additional function of passivating the surface recombination centers of the underlying photoelectrode. These functional components are precisely assembled on a model photoanode (e.g., Fe₂O₃ and BiVO₄) in a desired order and various combinations without degradation of their intrinsic properties. As a result, the performance of water oxidation photoanodes is synergistically enhanced. This study can enable the design and fabrication of novel solar‐to‐chemical energy conversion devices.     

Hematite Photoanodes: Synergetic Enhancement of Light Harvesting and Charge Management by Sandwiched with Fe2TiO5/Fe2O3/Pt Structures

Efficient charge separation and transport as well as high light absorption are key factors that determine the efficiency of photoelectrochemical (PEC) water splitting devices. Here, a PEC device consisting of a hematite nanoporous film deposited on Pt nanopillars, followed by the decoration with an Fe₂TiO₅ passivation layer, is designed and fabricated. This structure can largely improve the light absorption in the composite materials, and significantly enhance the water oxidation performance of hematite photoanodes. The Fe₂TiO₅ thin shell and Pt underlayer significantly improve the interfacial charge transfer while minimizing the hole‐migration length in Fe₂O₃ photoanodes, leading to a drastically increased photocurrent density. Specially, the Fe₂TiO₅/Fe₂O₃/Pt photoanode yields an excellent photoresponse for PEC water splitting reactions with 1.0 and 2.4 mA cm^?2 obtained at 1.23 and 1.6 V_RHE under AM 1.5G illumination in 1 m KOH. The resulting photocurrents are 2.5 times enhanced compared to a pristine Fe₂O₃ photoanode of the same geometry. These results demonstrate a synergistic charge transfer effect of Fe₂TiO₅ and Pt layers on hematite for the improvement of PEC water oxidation.     

Zinc Ferrite Photoanode Nanomorphologies with Favorable Kinetics for Water‐Splitting

The n‐type semiconducting spinel zinc ferrite (ZnFe₂O₄) is used as a photoabsorber material for light‐driven water‐splitting. It is prepared for the first time by atomic layer deposition. Using the resulting well‐defined thin films as a model system, the performance of ZnFe₂O₄ in photoelectrochemical water oxidation is characterized. Compared to benchmark α‐Fe₂O₃ (hematite) films, ZnFe₂O₄ thin films achieve a lower photocurrent at the reversible potential. However, the oxidation onset potential of ZnFe₂O₄ is 200 mV more cathodic, allowing the water‐splitting reaction to proceed at a lower external bias and resulting in a maximum applied‐bias power efficiency (ABPE) similar to that of Fe₂O₃. The kinetics of the water oxidation reaction are examined by intensity‐modulated photocurrent spectroscopy. The data indicate a considerably higher charge transfer efficiency of ZnFe₂O₄ at potentials between 0.8 and 1.3 V versus the reversible hydrogen electrode, attributable to significantly slower surface charge recombination. Finally, nanostructured ZnFe₂O₄ photoanodes employing a macroporous antimony‐doped tin oxide current collector reach a five times higher photocurrent than the flat films. The maximum ABPE of these host–guest photoanodes is similarly increased.     

Tungsten Trioxide Nanostructures for Photoelectrochemical Water Splitting: Material Engineering and Charge Carrier Dynamic Manipulation

To address the energy crisis and environmental problems, the applications of solar energy have received intensive attention. Converting solar energy to hydrogen using a photoelectrochemical (PEC) cell is one of the most promising approaches to meet future energy demands. As an earth abundant metal oxide, tungsten trioxide (WO₃), which has a moderate band gap (2.5–2.7 eV), ideal valence band position, and high resistance to photocorrosion, has been widely utilized in PEC photoanodes. To obtain a WO₃ photoanode with high PEC efficiency, tremendous efforts have been made to improve the light absorption capacity, charge carrier dynamics, and oxygen evolution activity. In this report, the recent advances in WO₃ photoanode optimization, including morphology design, dopants doping, heterojunction fabrication, and surface modification are summarized. In this review, these developments and representative applications of WO₃ photoanodes in unassisted water splitting devices are also discussed. Finally, perspectives on the significant challenges and future prospects for the development of WO₃ photoanodes for PEC water splitting are provided.     

Carbon Nanotube–Graphitic Carbon Nitride Hybrid Films for Flavoenzyme‐Catalyzed Photoelectrochemical Cells

In green plants, solar‐powered electrons are transferred through sophistically arranged photosystems and are subsequently channelled into the Calvin cycle to generate chemical energy. Inspired by the natural photosynthetic scheme, a photoelectrochemical cell (PEC) is constructed configured with protonated graphitic carbon nitride (p‐g‐C₃N₄) and carbon nanotube hybrid (CNT/p‐g‐C₃N₄) film cathode, and FeOOH‐deposited bismuth vanadate (FeOOH/BiVO₄) photoanode for the production of industrially useful chiral alkanes using an old yellow enzyme homologue from Thermus scotoductus (TsOYE). In the biocatalytic PEC platform, photoexcited electrons provided by the FeOOH/BiVO₄ photoanode are transferred to the robust and self‐standing CNT/p‐g‐C₃N₄ hybrid film that electrocatalytically reduces flavin mononucleotide (FMN) mediator. The p‐g‐C₃N₄ promotes a two‐electron reduction of FMN coupled with an accelerated electron transfer by the conductive CNT network. The reduced FMN subsequently delivers the electrons to TsOYE for the highly enantioselective conversion of ketoisophorone to (R)‐levodione. Under light illumination (>420 nm) and external bias, (R)‐levodione is synthesized with the enantiomeric excess value of above 83%, not influenced by the scale of applied bias, simultaneously exhibiting stable and high current efficiency. The results suggest that the biocatalytic PEC made up of economical materials can selectively synthesize high‐value organic chemicals using water as an electron donor.     

Hematite Films Decorated with Nanostructured Ferric Oxyhydroxide as Photoanodes for Efficient and Stable Photoelectrochemical Water Splitting

Hematite photoanodes are decorated with nanostructured FeOOH by photoelectrodeposition. An obvious cathodic shift in the photocurrent onset potential is observed, while four‐times enhancement of photocurrent density enhancement is acheived with FeOOH present. This can be ascribed to the high reaction area for the structure and high electrocatalytic activity of nanostructured FeOOH, which increases the amount of photogenerated holes involved in the water oxidation reaction and accelerates the kinetics of water oxidation. Furthermore, the obtained Fe₂O₃/FeOOH photoanode achieves considerable O₂ evolution rate (10.1 μmol h^?1 cm^?2) under AM 1.5 G illumination and is maintained for as long as 70 h. The Fe₂O₃/FeOOH films show visible light response, high photocurrent density, and long‐term stability, and they are well qualified photoanode materials and a promising candidate for photoelectrochemical water splitting.     

Bifunctional Perovskite-BiVO4 Tandem Devices for Uninterrupted Solar and Electrocatalytic Water Splitting Cycles

Photoelectrochemical (PEC) fuel synthesis depends on the intermittent solar intensity of the diurnal cycle and ceases at night. Here, an integrated device that does not only possess PEC water splitting functionality, but also operates as an electrolyzer in the nocturnal period to improve the overall capacity factor is described. The bifunctional system is based on an “artificial leaf” tandem PEC architecture that contains an inverse-structure lead halide perovskite protected by a graphite epoxy/parylene-C coating (conferring 96 h stability of operation in water), and a porous BiVO₄ semiconductor. The light-absorbers are interfaced with a H₂ evolution catalyst (Pt) and a Co-based water oxidation catalyst, respectively, which can also be directly driven by electricity. Thus, the device can operate in PEC mode during irradiation and switch to an electricity-powered mode in the dark through bypassing of the semiconductor configuration. The bifunctional perovskite-BiVO₄ tandem provides a solar-to-hydrogen efficiency of 1.3% under simulated solar irradiation and an onset for water electrolysis at 1.8 V. The compact design and low cost of the proposed device may provide an advantage over other technologies for round-the-clock fuel production.     

Effects of Structural Variation on the Photocatalytic Performance of Hydrothermally Synthesized BiVO4

Highly crystalline monoclinic scheelite BiVO₄ powders are synthesized from aqueous Bi(NO₃)₃ and NH₄VO₃ solutions over a wide range of pH by a hydrothermal process. BiVO₄ powders with various morphologies, surface textures, and grain shapes are selectively synthesized by adjusting the pH. The dependence of the Raman peak position and intensity on the synthesis conditions indicates that the symmetry distortions in the local structure of the synthesized BiVO₄ are affected by the preparation conditions. These variations in the local structure result in the modification of the electronic structure of BiVO₄, which results in a blue‐shift in the UV‐vis absorption spectrum of hydrothermally synthesized BiVO₄ in comparison with a well‐crystallized sample prepared by homogeneous coprecipitation. The photocatalytic activities for O₂ evolution from an aqueous AgNO₃ solution under visible‐light irradiation are strongly dependent on the pH used in the synthesis. The differences in the photocatalytic activities between BiVO₄ samples prepared under various conditions is attributed to the degree of structural distortion, leading to differences in the mobility of photogenerated holes formed in the valence band, which consists of Bi 6s and O 2p orbitals.     

Improved Photocatalytic Performance of Heterojunction by Controlling the Contact Facet: High Electron Transfer Capacity between TiO2 and the {110} Facet of BiVO4 Caused by Suitable Energy Band Alignment

Charge separation at the interface of heterojunctions is affected by the energy band alignments of the materials that compose the heterojunctions. Controlling the contact crystal facets can lead to different energy band alignments owing to the varied electronic structures of the different crystal facets. Therefore, BiVO₄‐TiO₂ heterojunctions are designed with different BiVO₄ crystal facets at the interface ({110} facet or {010} facet), named BiVO₄‐110‐TiO₂ and BiVO₄‐010‐TiO₂, respectively, to achieve high photocatalytic performance. Higher photocurrent density and lower photoluminescence intensity are observed with the BiVO₄‐110‐TiO₂ heterojunction than those of the BiVO₄‐010‐TiO₂ heterojunction, which confirms that the former possesses higher charge carrier separation capacity than the latter. The photocatalytic degradation results of both Rhodamine B and 4‐nonylphenol demonstrate that better photocatalytic performance is achieved on the BiVO₄‐110‐TiO₂ heterojunction than the BiVO₄‐010‐TiO₂ heterojunction under visible light (≥422 nm) irradiation. The higher electron transfer capacity and better photocatalytic performance of the BiVO₄‐110‐TiO₂ heterojunction are attributed to the more fluent electron transfer from the {110} facet of BiVO₄ to TiO₂ caused by the smaller interfacial energy barrier. This is further confirmed by the selective deposition of Pt on the TiO₂ surface as well as the longer lifetime of Bi⁵⁺ in the BiVO₄‐110‐TiO₂ heterojunction.     

Synergistic Effect of Si Doping and Heat Treatments Enhances the Photoelectrochemical Water Oxidation Performance of TiO2 Nanorod Arrays

TiO₂ is a very promising photocatalytic material due to its merits including low cost, nontoxicity, high chemical stability, and photocorrosion resistance. However, it is also known that TiO₂ is a wide bandgap material, and it is still challenging to achieve high photocatalytic performance driven by solar light. In this paper, silicon‐doped TiO₂ nanorod arrays are vertically grown on fluorine‐doped tin oxide substrates and then are heat treated both in air and in vacuum. It is found that the silicon doping together with the heat treatment brings synergic effect to TiO₂ nanorod films by increasing the crystallinity, producing abundant oxygen vacancies, enhancing the hydrophilicity as well as improving the electronic properties. When used as photoanodes in photoelectrochemical water splitting, under the condition of AM 1.5G simulated solar irradiation and without using any cocatalysts, these nanorod films show photocurrent density as high as 0.83 mA cm^?2 at a potential of 1.23 V versus reversible hydrogen electrode, which is much higher than that of the TiO₂ nanorod films without doping or heat treating. The silicon‐doped TiO₂ nanorod array films described in this paper are envisioned to provide valuable platforms for supporting catalysts and cocatalysts for efficient solar‐light‐assisted water oxidation and other solar‐light‐driven photocatalytic applications.     

Photoelectrochemical Water Oxidation by GaAs Nanowire Arrays Protected with Atomic Layer Deposited NiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Electrocatalysts

Photoelectrochemical (PEC) hydrogen production makes possible the direct conversion of solar energy into chemical fuel. In this work, PEC photoanodes consisting of GaAs nanowire (NW) arrays were fabricated, characterized, and then demonstrated for the oxygen evolution reaction (OER). Uniform and periodic GaAs nanowire arrays were grown on a heavily n-doped GaAs substrates by metal–organic chemical vapor deposition selective area growth. The nanowire arrays were characterized using cyclic voltammetry and impedance spectroscopy in a non-aqueous electrochemical system using ferrocene/ferrocenium (Fc/Fc+) as a redox couple, and a maximum oxidation photocurrent of 11.1 mA/cm² was measured. GaAs NW arrays with a 36 nm layer of nickel oxide (NiO _x ) synthesized by atomic layer deposition were then used as photoanodes to drive the OER. In addition to acting as an electrocatalyst, the NiO _x layer served to protect the GaAs NWs from oxidative corrosion. Using this strategy, GaAs NW photoanodes were successfully used for the oxygen evolution reaction. This is the first demonstration of GaAs NW arrays for effective OER, and the fabrication and protection strategy developed in this work can be extended to study any other nanostructured semiconductor materials systems for electrochemical solar energy conversion.     

Metal‐Insulator Transition in ALD VO2 Ultrathin Films and Nanoparticles: Morphological Control

Nanoscale morphology of vanadium dioxide (VO₂) films can be controlled to realize smooth ultrathin (<10 nm) crystalline films or nanoparticles with atomic layer deposition, opening doors to practical VO₂ metal‐insulator transition (MIT) nanoelectronics. The precursor combination, the valence of V, and the density for as‐deposited VO₂ films, as well as the postdeposition crystallization annealing conditions determine whether a continuous thin film or nanoparticle morphology is obtained. It is demonstrated that the films and particles possess both a structural and an electronic transition. The resistivity of ultrathin films changes by more than two orders of magnitude across the MIT, demonstrating their high quality.     

Highly Efficient Sn/Pb Binary Perovskite Solar Cell via Precursor Engineering: A Two‐Step Fabrication Process

Regulation of the crystallization of perovskite films and avoiding the oxidation of Sn²⁺ during the deposition process are very important for achieving Sn/Pb binary perovskite solar cells (PVSCs) with high power conversion efficiency (PCE) and producibility. In this work, a high‐quality HC(NH₂)₂Pb_0.7Sn_0.3I₃ (FAPb_0.7Sn_0.3I₃) film deposited from the two‐step solution process by introducing methylammonium thiocyanate (MASCN) as a bifunctional additive into the precursor solution containing PbI₂ and SnI₂ is reported. MASCN can not only tune the morphology of the perovskite film but also stabilize the precursor solution via retarding the oxidation of Sn²⁺ through a strong coordination between SCN^? and Sn²⁺. The Sn/Pb binary inverted PVSCs based on FAPb_0.7Sn_0.3I₃ present a high fill factor of 0.79 and the best PCE of 16.26% in the case of 0.25 MASCN addition. The device fabrication producibility is also greatly improved due to the stabilized precursor solution with the aid of MASCN. The PCE of the device is almost independent of the storage time of the precursor solution within 124 d in the N₂‐filled glove box. These results indicate that the precursor engineering with multifunctionality additive is an effective approach toward highly efficient and producible PVSCs for future commercialization.