Self-Supported Pd Nanorod Arrays for High-Efficient Nitrate Electroreduction to Ammonia

Electrochemical nitrate (NO₃⁻) reduction to ammonia (NH₃) offers a promising pathway to recover NO₃⁻ pollutants from industrial wastewater that can balance the nitrogen cycle and sustainable green NH₃ production. However, the efficiency of electrocatalytic NO₃⁻ reduction to NH₃ synthesis remains low for most of electrocatalysts due to complex reaction processes and severe hydrogen precipitation reaction. Herein, high performance of nitrate reduction reaction (NO₃⁻RR) is demonstrated on self-supported Pd nanorod arrays in porous nickel framework foam (Pd/NF). It provides a lot of active sites for H* adsorption and NO₃⁻ activation leading to a remarkable NH₃ yield rate of 1.52 mmol cm⁻² h⁻¹ and a Faradaic efficiency of 78% at −1.4 V versus RHE. Notably, it maintains a high NH₃ yield rate over 50 cycles in 25 h showing good stability. Remarkably, large-area Pd/NF electrode (25 cm²) shows a NH₃ yield of 174.25 mg h⁻¹, be promising candidate for large-area device for industrial application. In situ FTIR spectroscopy and density functional theory calculations analysis confirm that the enrichment effect of Pd nanorods encourages the adsorption of H species for ammonia synthesis following a hydrogenation mechanism. This work brings a useful strategy for designing NO₃⁻RR catalysts of nanorod arrays with customizable compositions.     

Regulating the Electronic Structure of Bismuth Nanosheets by Titanium Doping to Boost CO2 Electroreduction and Zn–CO2 Batteries

The electrochemical carbon dioxide reduction reaction (E-CO₂RR) to formate is a promising strategy for mitigating greenhouse gas emissions and addressing the global energy crisis. Developing low-cost and environmentally friendly electrocatalysts with high selectivity and industrial current densities for formate production is an ideal but challenging goal in the field of electrocatalysis. Herein, novel titanium-doped bismuth nanosheets (Ti Bi NSs) with enhanced E-CO₂RR performance are synthesized through one-step electrochemical reduction of bismuth titanate (Bi₄Ti₃O₁₂). We comprehensively evaluated Ti Bi NSs using in situ Raman spectra, finite element method, and density functional theory. The results indicate that the ultrathin nanosheet structure of Ti Bi NSs can accelerate mass transfer, while the electron-rich properties can accelerate the production of *CO₂⁻ and enhance the adsorption strength of *OCHO intermediate. The Ti Bi NSs deliver a high formate Faradaic efficiency (FE_formate) of 96.3% and a formate production rate of 4032 µmol h⁻¹ cm⁻² at −1.01 V versus RHE. An ultra-high current density of −338.3 mA cm⁻² is achieved at −1.25 versus RHE, and simultaneously FE_formate still reaches more than 90%. Furthermore, the rechargeable Zn–CO₂ battery using Ti Bi NSs as a cathode catalyst achieves a maximum power density of 1.05 mW cm⁻² and excellent charging/discharging stability of 27 h.     

Constructing Co@TiO2 Nanoarray Heterostructure with Schottky Contact for Selective Electrocatalytic Nitrate Reduction to Ammonia

Electrochemical nitrate (NO₃⁻) reduction reaction (NO₃⁻RR) is a potential sustainable route for large-scale ambient ammonia (NH₃) synthesis and regulating the nitrogen cycle. However, as this reaction involves multi-electron transfer steps, it urgently needs efficient electrocatalysts on promoting NH₃ selectivity. Herein, a rational design of Co nanoparticles anchored on TiO₂ nanobelt array on titanium plate (Co@TiO₂/TP) is presented as a high-efficiency electrocatalyst for NO₃⁻RR. Density theory calculations demonstrate that the constructed Schottky heterostructures coupling metallic Co with semiconductor TiO₂ develop a built-in electric field, which can accelerate the rate determining step and facilitate NO₃⁻ adsorption, ensuring the selective conversion to NH₃. Expectantly, the Co@TiO₂/TP electrocatalyst attains an excellent Faradaic efficiency of 96.7% and a high NH₃ yield of 800.0 µmol h⁻¹ cm⁻² under neutral solution. More importantly, Co@TiO₂/TP heterostructure catalyst also presents a remarkable stability in 50-h electrolysis test.     

Light Field-Enhanced Single-Site Cu Electrocatalyst for Nitrogen Fixation

Direct electrocatalytic reduction of N₂ to NH₃ under mild conditions is attracting considerable interests but still remains enormous challenges in terms of respect of intrinsic catalytic activity and limited electrocatalytic efficiency. Herein, a photo-enhanced strategy is developed to improve the NRR activity on Cu single atoms catalysts. The atomically dispersed Cu single atoms supported TiO₂ nanosheets (Cu SAs/TiO₂) achieve a Faradaic Efficiency (12.88%) and NH₃ yield rate (6.26 µg h⁻¹ mg_cat⁻¹) at −0.05 V versus RHE under the light irradiation field, in which NH₃ yield rate is fivefold higher than that under pure electrocatalytic nitrogen reduction reaction (NRR) process and is remarkably superior in comparison to most of the similar type electrocatalysts. The existence of external light field improves electron transfer ability between Cu O and Ti O, and thus optimizes the accumulation of surface charges on Cu sites, endowing more electrons involved in nitrogen fixation. This work reveals an atomic-scale mechanistic understanding of field effect-enhanced electrochemical performance of catalysts and it provides predictive guidelines for the rational design of photo-enhanced electrochemical N₂ reduction catalysts.     

Accelerating Industrial-Level NO3− Electroreduction to Ammonia on Cu Grain Boundary Sites via Heteroatom Doping Strategy

Although the electrocatalytic nitrate reduction reaction (NO₃⁻RR) is an attractive NH₃ synthesis route, it suffers from low yield due to the lack of efficient catalysts. Here, this work reports a novel grain boundary (GB)-rich Sn-Cu catalyst, derived from in situ electroreduction of Sn-doped CuO nanoflower, for effectively electrochemical converting NO₃⁻ to NH₃. The optimized Sn_1%-Cu electrode achieves a high NH₃ yield rate of 1.98 mmol h⁻¹ cm⁻² with an industrial-level current density of −425 mA cm⁻² at −0.55 V versus a reversible hydrogen electrode (RHE) and a maximum Faradaic efficiency of 98.2% at −0.51 V versus RHE, outperforming the pure Cu electrode. In situ Raman and attenuated total reflection Fourier transform infrared spectroscopies reveal the reaction pathway of NO₃⁻RR to NH₃ by monitoring the adsorption property of reaction intermediates. Density functional theory calculations clarify that the high-density GB active sites and the competitive hydrogen evolution reaction (HER) suppression induced by Sn doping synergistically promote highly active and selective NH₃ synthesis from NO₃⁻RR. This work paves an avenue for efficient NH₃ synthesis over Cu catalyst by in situ reconstruction of GB sites with heteroatom doping.     

Pd-Doped Co3O4 Nanoarray for Efficient Eight-Electron Nitrate Electrocatalytic Reduction to Ammonia Synthesis

Ammonia (NH₃) is an indispensable feedstock for fertilizer production and one of the most ideal green hydrogen rich fuel. Electrochemical nitrate (NO₃⁻) reduction reaction (NO₃⁻RR) is being explored as a promising strategy for green to synthesize industrial-scale NH₃, which has nonetheless involved complex multi-reaction process. This work presents a Pd-doped Co₃O₄ nanoarray on titanium mesh (Pd-Co₃O₄/TM) electrode for highly efficient and selective electrocatalytic NO₃⁻RR to NH₃ at low onset potential. The well-designed Pd-Co₃O₄/TM delivers a large NH₃ yield of 745.6 µmol h⁻¹ cm⁻² and an extremely high Faradaic efficiency (FE) of 98.7% at −0.3 V with strong stability. These calculations further indicate that the doping Co₃O₄ with Pd improves the adsorption characteristic of Pd-Co₃O₄ and optimizes the free energies for intermediates, thereby facilitating the kinetics of the reaction. Furthermore, assembling this catalyst in a Zn-NO₃⁻ battery realizes a power density of 3.9 mW cm⁻² and an excellent FE of 98.8% for NH₃.     

Interfacially Engineered Nanoporous Cu/MnOx Hybrids for Highly Efficient Electrochemical Ammonia Synthesis via Nitrate Reduction

Electrochemical reduction of nitrate to ammonia (NH₃) not only offers a promising strategy for green NH₃ synthesis, but also addresses the environmental issues and balances the perturbed nitrogen cycle. However, current electrocatalytic nitrate reduction processes are still inefficient due to the lack of effective electrocatalysts. Here 3D nanoporous Cu/MnO_x hybrids are reported as efficient and durable electrocatalysts for nitrate reduction reaction, achieving the NH₃ yield rates of 5.53 and 29.3 mg h⁻¹ mg_cat.⁻¹ with 98.2% and 86.2% Faradic efficiency in 0.1 m Na₂SO₄ solution with 10 and 100 mm KNO₃, respectively, which are higher than those obtained for most of the reported catalysts under similar conditions. Both the experimental results and density functional theory calculations reveal that the interface effect between Cu/MnO_x interface could reduce the free energy of rate determining step and suppress the hydrogen evolution reaction, leading to the enhanced catalytic activity and selectivity. This work provides an approach to design advanced materials for NH₃ production via electrochemical nitrate reduction.     

Microenvironment Engineering to Promote Selective Ammonia Electrosynthesis from Nitrate over a PdCu Hollow Catalyst

The electrosynthesis of recyclable ammonia (NH₃) from nitrate under ambient conditions is of great importance but still full of challenges for practical application. Herein, an efficient catalyst design strategy is developed that can engineer the surface microenvironment of a PdCu hollow (PdCu-H) catalyst to confine the intermediates and thus promote selective NH₃ electrosynthesis from nitrate. The hollow nanoparticles are synthesized by in situ reduction and nucleation of PdCu nanocrystals along a self-assembled micelle of a well-designed surfactant. The PdCu-H catalyst shows a structure-dependent selectivity toward the NH₃ product during the nitrate reduction reaction (NO₃⁻RR) electrocatalysis, enabling a high NH₃ Faradaic efficiency of 87.3% and a remarkable NH₃ yield rate of 0.551 mmol h⁻¹ mg⁻¹ at -0.30 V (vs reversible hydrogen electrode). Moreover, this PdCu-H catalyst delivers high electrochemical performance in the rechargeable zinc-NO₃⁻ battery. These results provide a promising design strategy to tune catalytic selectivity for efficient electrosynthesis of renewable NH₃ and feedstocks.     

Dinitrogen Reduction Coupled with Methanol Oxidation for Low Overpotential Electrochemical NH3 Synthesis Over Cobalt Pyrophosphate as Bifunctional Catalyst

Electrochemical dinitrogen (N₂) reduction to ammonia (NH₃) coupled with methanol electro-oxidation is presented in the current work. Here, methanol oxidation reaction (MOR) is proposed as an alternative anode reaction to oxygen evolution reaction (OER) to accomplish electrons-induced reduction of N₂ to NH₃ at cathode and oxidation of methanol at anode in alkaline media thereby reducing the overall cell voltage for ammonia production. Cobalt pyrophosphate micro-flowers assembled by nanosheets are synthesized via a surfactant-assisted sonochemical approach. By virtue of structural and morphological advantages, the maximum Faradaic efficiency of 43.37% and NH₃ yield rate of 159.6 µg h⁻¹ mg_ca⁻¹ is achieved at a potential of −0.2 V versus RHE. The proposed catalyst is shown to also exhibit a very high activity (100 mA mg⁻¹ at 1.48 V), durability (2 h) and production of value-added formic acid at anode (2.78 µmol h⁻¹ mg_cat⁻¹ and F.E. of 59.2%). The overall NH₃ synthesis is achieved at a reduced cell voltage of 1.6 V (200 mV less than NRR-OER coupled NH₃ synthesis) when OER at anode is replaced with MOR and a high NH₃ yield rate of 95.2 µg h⁻¹ mg_cat⁻¹ and HCOOH formation rate of 2.53 µmol h⁻¹ mg⁻¹ are witnessed under full-cell conditions.     

Porous and Partially Dehydrogenated Fe2+-Containing Iron Oxyhydroxide Nanosheets for Efficient Electrochemical Nitrogen Reduction Reaction (ENRR)

The design and development of efficient catalysts for electrochemical nitrogen reduction reaction (ENRR) under ambient conditions are critical for the alternative ammonia (NH₃) synthesis from N₂ and H₂O, wherein iron-based electrocatalysts exhibit outstanding NH₃ formation rate and Faradaic efficiency (FE). Here, the synthesis of porous and positively charged iron oxyhydroxide nanosheets by using layered ferrous hydroxide as a starting precursor, which undergoes topochemical oxidation, partial dehydrogenated reaction, and final delamination, is reported. As the electrocatalyst of ENRR, the obtained nanosheets with a monolayer thickness and 10-nm mesopores display exceptional NH₃ yield rate (28.5 µg h⁻¹ mg_cat.⁻¹) and FE (13.2%) at a potential of −0.4 V versus RHE in a phosphate buffered saline (PBS) electrolyte. The values are much higher than those of the undelaminated bulk iron oxyhydroxide. The larger specific surface area and positive charge of the nanosheets are beneficial for providing more exposed reactive sites as well as retarding hydrogen evolution reaction. This study highlights the rational control on the electronic structure and morphology of porous iron oxyhydroxide nanosheets, expanding the scope of developing non-precious iron-based highly efficient ENRR electrocatalysts.     

Phosphorus‐Doped Iron Nitride Nanoparticles Encapsulated by Nitrogen‐Doped Carbon Nanosheets on Iron Foam In Situ Derived from Saccharomycetes Cerevisiae for Electrocatalytic Overall Water Splitting

It is vitally essential to propose a novel, economical, and safe preparation method to design highly efficient electrocatalysts. Herein, phosphorus‐doped iron nitride nanoparticles encapsulated by nitrogen‐doped carbon nanosheets are grown directly on the iron foam substrate (P‐Fe₃N@NC NSs/IF) by in situ deriving from Saccharomycetes cerevisiae (S. cerevisiae), where anion elements of C, N, and P all from S. cerevisiae replace the hazardous CH₄, NH₃, and H₃P. The diffusion pattern of N, P in S. cerevisiae and contact form between metal and S. cerevisiae observably affect the composition and phase of the product during high‐temperature calcination. The obtained P‐Fe₃N@NC NSs/IF demonstrates superior electrocatalytic performance for the hydrogen evolution reaction and oxygen evolution reaction, also satisfying durability. Theoretical calculation confirms that Fe sites of P‐Fe₃N serve as the active center, and N sites and P doping regulate the hydrogen binding strength to enhance catalytic ability. Additionally, the two‐electrode electrolyzer assembled by P‐Fe₃N@NC NSs/IF as both anode and cathode electrodes needs only 1.61 V to reach 10 mA cm^?2 for overall water splitting with a superb stability. The S. cerevisiae‐based process presents a feasible approach for synthesis of nitrides, carbides, phosphides, and electrocatalytic applications.     

Coupling Engineering of NH4+ Pre-Intercalation and Rich Oxygen Vacancies in Tunnel WO3 Toward Fast and Stable Rocking Chair Zinc-Ion Battery

Herein, for the first time, a pre-intercalated non-metal ion (NH₄⁺) with rich oxygen vacancies stabilized tunnel WO₃ is proposed as a new intercalation anode to construct Zn-metal-free rocking-chair ZIBs. With the ethylene glycol additive in the aqueous electrolyte, the Zn²⁺ solvation structure can be regulated and the side reaction of hydrogen evolution can also be suppressed. Owing to the integrated synergetic modification, a high-rate and ultra-stable aqueous Zn-(NH₄)_xWO₃ battery can be constructed, which exhibits an improved specific capacity (153 mAh g⁻¹ at 0.1 A g⁻¹), excellent rate performance (when the current density increases to 3 A g⁻¹, the specific capacitance is still 86 mAh g⁻¹), and a high cycle stability with 100% capacity retention after 2,200 cycles under 5 A g⁻¹. Ex situ X-ray diffraction and XPS reveal the reversible insertion/extraction of Zn²⁺ in (NH₄)_xWO₃. The assembled (NH₄)_xWO₃//MnO₂ rocking-chair ZIBs delivers excellent capacity of 82 mAh g⁻¹ at 0.1 A g⁻¹, impressive cyclic stability. Additionally, the flexible (NH₄)_xWO₃//MnO₂ ZIBs can power the electrochromic device-based PANI/WO₃ with high color contrast and fast response time. This study provides new insight for developing high-performance rechargeable aqueous ZIBs.     

Atomically Dispersed Ni–N4 Sites Assist Pt3Ni Nanocages with Pt Skin to Synergistically Enhance Oxygen Reduction Activity and Stability

Currently, the rarity and high cost of platinum (Pt)-based electrocatalysts seriously limit their commercial application in fuel cells cathode. Decorating Pt with atomically dispersed metal–nitrogen sites possibly offers an effective pathway to synergy tailor their catalytic activity and stability. Here active and stable oxygen reduction reaction (ORR) electrocatalysts (Pt₃Ni@Ni–N₄–C) by in situ loading Pt₃Ni nanocages with Pt skin on single-atom nickel–nitrogen (Ni–N₄) embedded carbon supports are designed and constructed. The Pt₃Ni@Ni–N₄–C exhibits excellent mass activity (MA) of 1.92 A mg_Pt⁻¹ and specific activity of 2.65 mA cm_Pt⁻², together with superior durability of 10 mV decay in half-wave potential and only 2.1% loss in MA after 30 000 cycles. Theoretical calculations demonstrate that Ni–N₄ sites significant redistribute of electrons and make them transfer from both the adjacent carbon and Pt atoms to the Ni–N₄. The resultant electron accumulation region successfully anchored Pt₃Ni, that not only improves structural stability of the Pt₃Ni, but importantly makes the surface Pt more positive to weaken the adsorption of *OH to enhance ORR activity. This strategy lays the groundwork for the development of super effective and durable Pt-based ORR catalysts.     

Embedding Ru Clusters and Single Atoms into Perovskite Oxide Boosts Nitrogen Fixation and Affords Ultrahigh Ammonia Yield Rate

Ammonia is a key chemical feedstock worldwide. Compared with the well-known Haber–Bosch method, electrocatalytic nitrogen reduction reaction (ENRR) can eventually consume less energy and have less CO₂ emission. In this study, a plasma-enhanced chemical vapor deposition method is used to anchor transition metal element onto 2D conductive material. Among all attempts, Ru single-atom and Ru-cluster-embedded perovskite oxide are discovered with promising electrocatalysis performance for ENRR (NH₃ yield rate of up to 137.5 ± 5.8 µg h⁻¹ mg_cat⁻¹ and Faradaic efficiency of unexpected 56.9 ± 4.1%), reaching the top record of Ru-based catalysts reported so far. In situ experiments and density functional theory calculations confirm that the existence of Ru clusters can regulate the electronic structure of Ru single atoms and decrease the energy barrier of the first hydrogenation step (*NN to *NNH). Anchoring Ru onto various 2D perovskite oxides (LaMO-Ru, MCr, Mn, Co, or Ni) also show boosted ENRR performance. Not only this study provides an unique strategy toward transition-metal-anchored new 2D conductive materials, but also paves the way for fundamental understanding the correlation between cluster-involved single-atom sites and catalytic performance.     

Engineering Catalytically Active Sites by Sculpting Artificial Edges on MoS2 Basal Plane for Dinitrogen Reduction at a Low Overpotential

Engineering catalytically active sites have been a challenge so far and often relies on optimization of synthesis routes, which can at most provide quantitative enhancement of active facets, however, cannot provide control over choosing orientation, geometry and spatial distribution of the active sites. Artificially sculpting catalytically active sites via laser-etching technique can provide a new prospect in this field and offer a new species of nanocatalyst for achieving superior selectivity and attaining maximum yield via absolute control over defining their location and geometry of every active site at a nanoscale precision. In this work, a controlled protocol of artificial surface engineering is shown by focused laser irradiation on pristine MoS₂ flakes, which are confirmed as catalytic sites by electrodeposition of AuNPs. The preferential Au deposited catalytic sites are found to be electrochemically active for nitrogen adsorption and its subsequent reduction due to the S-vacancies rather than Mo-vacancy, as advocated by DFT analysis. The catalytic performance of Au-NR/MoS₂ shows a high yield rate of ammonia (11.43 × 10⁻⁸ mol s⁻¹ cm⁻²) at a potential as low as −0.1 V versus RHE and a notable Faradaic efficiency of 13.79% during the electrochemical nitrogen reduction in 0.1 m HCl.     

Controllable Exfoliation of MOF-Derived Van Der Waals Superstructure into Ultrathin 2D B/N Co-Doped Porous Carbon Nanosheets: A Superior Catalyst for Ambient Ammonia Electrosynthesis

The electrocatalytic nitrogen reduction reaction (NRR) to synthesize NH₃ under ambient conditions is a promising alternative route to the conventional Haber–Bosch process, but it is still a great challenge to develop electrocatalysts’ high Faraday efficiency and ammonia yield. Herein, a facile and efficient exfoliation strategy to synthesize ultrathin 2D boron and nitrogen co-doped porous carbon nanosheets (B/N C NS) via a metal–organic framework (MOF)-derived van der Waals superstructure, is reported. The results of experiments and theoretical calculations show that the doping of boron and nitrogen can modulate the electronic structure of the adjacent carbon atoms; which thus, promotes the competitive adsorption of nitrogen and reduces the energy required for ammonia synthesis. The B/N C NS exhibits excellent catalytic performance and stability in electrocatalytic NRR, with a yield rate of 153.4 µg·h⁻¹·mg⁻¹ cat and a Faraday efficiency of 33.1%, which is better than most of the reported NRR electrocatalysts. The ammonia yield of B/N C NS can maintain 92.7% of the initial NRR activity after 48 h stability test. The authors’ controllable exfoliation strategy using MOF-derived van der Waals superstructure can provide a new insight for the synthesis of other 2D materials.     

Rational Construction of Heterostructured Cu3P@TiO2 Nanoarray for High-Efficiency Electrochemical Nitrite Reduction to Ammonia

Electroreduction of nitrite (NO₂⁻) to valuable ammonia (NH₃) offers a sustainable and green approach for NH₃ synthesis. Here, a Cu₃P@TiO₂ heterostructure is rationally constructed as an active catalyst for selective NO₂⁻-to-NH₃ electroreduction, with rich nanosized Cu₃P anchored on a TiO₂ nanoribbon array on Ti plate (Cu₃P@TiO₂/TP). When performed in the 0.1 m NaOH with 0.1 m NaNO₂, the Cu₃P@TiO₂/TP electrode obtains a large NH₃ yield of 1583.4 µmol h⁻¹ cm⁻² and a high Faradaic efficiency of 97.1%. More importantly, Cu₃P@TiO₂/TP also delivers remarkable long-term stability for 50 h electrolysis. Theoretical calculations indicate that intermediate adsorption/conversion processes on Cu₃P@TiO₂ interfaces are synergistically optimized, substantially facilitating the conversion of NO₂⁻-to-NH₃.     

Defective TiO2−x for High-Performance Electrocatalytic NO Reduction toward Ambient NH3 Production

Synthesis of green ammonia (NH₃) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton-involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen-defective TiO₂ nanoarray supported on Ti plate (TiO_2−x/TP) behaves as an efficient catalyst for NO reduction to NH₃. In 0.2 m phosphate-buffered electrolyte, such TiO_2−x/TP shows competitive electrocatalytic NH₃ synthesis activity with a maximum NH₃ yield of 1233.2 µg h⁻¹ cm⁻² and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO_2−x (101) compared to perfect TiO₂ (101). And the low energy barrier of 0.7 eV on TiO_2−x (101) for the potential-determining step further highlights the greatly improved intrinsic activity. In addition, a Zn-NO battery is fabricated with TiO_2−x/TP and Zn plate to obtain an NH₃ yield of 241.7 µg h⁻¹ cm⁻² while providing a peak power density of 0.84 mW cm⁻².     

Ultrathin In2O3 Nanosheets toward High Responsivity and Rejection Ratio Visible-Blind UV Photodetection

Photoelectrochemical-type visible-blind ultraviolet photodetectors (PEC VBUV PDs) have gained ever-growing attention due to their simple fabrication processes, uncomplicated packaging technology, and high sensitivity. However, it is still challenging to achieve high-performance PEC VBUV PDs based on a single material with good spectral selectivity. Here, it is demonstrated that individual ultrathin indium oxide (In₂O₃) nanosheets (NSs) are suitable for designing high-performance PEC VBUV PDs with high responsivity and UV/visible rejection ratio for the first time. In₂O₃ NSs PEC PDs show excellent UV photodetection capability with an ultrahigh photoresponsivity of 172.36 mA W⁻¹ and a high specific detectivity of 4.43 × 10¹¹ Jones under 254 nm irradiation, which originates from the smaller charge transfer resistance (R_ct) at the In₂O₃ NSs/electrolyte interface. The light absorption of In₂O₃ NSs takes a blueshift due to the quantum confinement effect, granting good spectral selectivity for visible-blind detection. The UV/visible rejection ratio of In₂O₃ NSs PEC PDs is 1567, which is 30 times higher than that of In₂O₃ nanoparticles (NPs) and exceeds all recently reported PEC VBUV PDs. Moreover, In₂O₃ NSs PEC PDs show good stability and good underwater imaging capability. The results verify that ultrathin In₂O₃ NSs have potential in underwater optoelectronic devices.