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A co-modification strategy of transition metal V doping and heterostructure construction to promote the reconfiguration of active sites is reported. It synergistically improves the adsorption of water and urea molecules, and make the catalyst deliver excellent performance in alkaline urea assisted water splitting. Meanwhile, V doping promotes the formation of PO 3 −, which stabilizes the in-situ generated active site of V@NiOOH, leading to excellent stability. [Display omitted] • V doping promotes formation of Ni(PO 3) 2 /Ni 2 P heterojunction in phosphating process. • V doping accelerates in-situ reconstruction of active site during OER/UOR process. • Active site V@NiOOH reduces *COO adsorption energy compared to NiOOH during UOR. • V-Ni(PO 3) 2 /Ni 2 P exhibits excellent OER/UOR activity and stability in AEMWE. Efficient bifunctional electrocatalysts towards oxygen evolution reaction (OER) and urea electrooxidation reaction (UOR) are urgently needed for hydrogen production from urea-containing wastewater electrolysis. The main challenge lies in the sluggish UOR kinetics and the stability of catalyst under practical high current density. Here, a vanadium doped heterostructure of Ni(PO 3) 2 /Ni 2 P with shaggy nanosheet morphology was successfully synthesized. The doping of V atoms promotes the formation of Ni(PO 3) 2 /Ni 2 P heterojunction in phosphating process. It is demonstrated that V-doped Ni(PO 3) 2 /Ni 2 P accelerates the generation of real active site V@NiOOH in OER and UOR processes, which can also be stabilized by the PO 3 − ions. The in-situ formed V@NiOOH increases the adsorption energy of urea molecule, and reduces the adsorption energy of key intermediates *COO, thus facilitating the release of CO 2 product from the catalyst surface. The energy barrier of *HNCON to *NCON is also reduced dramatically, promoting the kinetics of UOR. In addition, the shaggy nanosheets morphology provides large number of catalytic sites and transport channels, which are conducive to mass transfer under high current density. As a result, the V-Ni(PO 3) 2 /Ni 2 P electrode based anion-exchange membrane (AEM) electrolyzer needs only 1.61 V to drive the total urea electrolysis at an industrial grade current density of 550 mA cm−2 with an outstanding durability of 700 h. This work paves the way for designing practical efficient and stable electrocatalyst for urea contained wastewater electrolysis to produce hydrogen. [ABSTRACT FROM AUTHOR]

The V-doped Ni 4 N@CuCoN 0.6 heterostructure with brush shape structure supported on the copper foam is prepared to serve as a high-performance UOR electrocatalyst at high current density, and Operando electrochemical impedance spectroscopy results exhibit direct oxidation for urea molecules on the surface of the catalyst. [Display omitted] • V-doping and heterostructure jointly adjust the electronic structure of catalysts. • The ability of electron transfer is improved by V-doping and heterostructure. • The direct oxidation of urea on the catalyst surface is confirmed by operando EIS. • Brush shape structure improves the capacity of bubble release and liquid transport. Exploring highly effective nickel-based catalytic materials for urea oxidation reaction (UOR) at high current density remains a challenging task for urea electrolysis. Herein, the vanadium-doped Ni 4 N@CuCoN 0.6 heterostructure with brush shape structure supported on copper foam (denoted as V-doped-Ni 4 N@CuCoN 0.6 /CF) is prepared to serve as a highly-performing UOR electrocatalyst at high current density (E 10/500/1000 = 1.26/1.40/1.45 V). Thanks to the construction of heterojunction, the local charge density undergoes redistribution at the V-doped-Ni 4 N@CuCoN 0.6 /CF interface between Ni 4 N and CuCoN 0.6 , thereby significantly enriching the active site and facilitating the adsorption process of urea molecules in a 1.0 M KOH + 0.5 M urea solution. Notably, V-doping exerts an additional influence by modulating the electronic structure of the catalyst, potentially optimizing the urea adsorption/CO 2 desorption process and reducing the energy barrier for the rate-determining step. Operando electrochemical impedance spectroscopy results show direct oxidation for urea molecules on the surface of V-doped-Ni 4 N@CuCoN 0.6 /CF, indicating that V-doping and heterostructure can effectively improve electron transfer. Furthermore, because the brush shape structure can be beneficial for bubble release and liquid transport on the catalyst's surface, for UOR stability, V-doped-Ni 4 N@CuCoN 0.6 /CF can maintain at 500 mA cm−2 for 80 h. Overall, this work suggests a highly-performing UOR electrocatalyst and provides a promising strategy for developing highly-efficient catalysts for UOR applications. [ABSTRACT FROM AUTHOR]

Phase engineering is a critical strategy in electrocatalysis, as it allows for the modulation of electronic, geometric, and chemical properties to directly influence the catalytic performance. Despite its potential, phase engineering remains particularly challenging in thermodynamically stable perovskites, especially in a 2D structure constraint. Herein, we report phase engineering in 2D LaNiO3 perovskite using the strongly non‐equilibrium microwave shock method. This approach enables the synthesis of conventional hexagonal and unconventional trigonal and cubic phases in LaNiO3 by inducing selective phase transitions at designed temperatures, followed by rapid quenching to allow precise phase control while preserving the 2D porous structure. These phase transitions induce structural distortions in the [LaO]+ layers and the hybridization between Ni 3d and O 2p states, modifying local charge distribution and enhancing electron transport during the six‐electron urea oxidation process (UOR). The cubic LaNiO3 offers optimal electron transport and active site accessibility due to its high structural symmetry and open interlayer spacing, resulting in a low onset potential of 1.27 V and a Tafel slope of 33.1 mV dec−1 for UOR, outperforming most current catalysts. Our strategy features high designability in phase engineering, enabling various electrocatalysts to harness the power of unconventional phases. [ABSTRACT FROM AUTHOR]

The oxygen vacancy-rich cobalt hydroxide/aluminum oxyhydroxide heterostructure is prepared through a facile one-step hydrothermal method, which exhibits superior electrocatalytic activity towards hydrogen evolution reaction (HER), and urea oxidation reaction (UOR). [Display omitted] Designing inexpensive, high-efficiency and durable bifunctional catalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) is an encouraging tactic to produce hydrogen with reduced energy expenditure. Herein, oxygen vacancy-rich cobalt hydroxide/aluminum oxyhydroxide heterostructure on nickel foam (denoted as Co(OH) 2 /AlOOH/NF-100) has been fabricated using one step hydrothermal process. Theoretical calculation and experimental results indicate the electrons transfer from Co(OH) 2 to highly active AlOOH results in the interfacial charge redistribution and optimization of electronic structure. Abundant oxygen vacancies in the heterostructure could improve the conductivity and simultaneously serve as the active sites for catalytic reaction. Consequently, the optimal Co(OH) 2 /AlOOH/NF-100 demonstrates excellent electrocatalytic performance for HER (62.9 mV@10 mA cm-2) and UOR (1.36 V@10 mA cm-2) due to the synergy between heterointerface and oxygen vacancies. Additionally, the in situ electrochemical impedance spectrum (EIS) for UOR suggests that the heterostructured catalyst exhibits rapid reaction kinetics, mass transfer and current response. Importantly, the urea-assisted electrolysis composed of the Co(OH) 2 /AlOOH/NF-100 manifests a low cell voltage (1.48 V @ 10 mA cm-2) in 1 M KOH containing 0.5 M urea. This work presents a promising avenue to the development of HER/UOR bifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

Urea oxidation reaction (UOR) instead of anodic oxygen evolution reaction (OER) is considered an effective way to reduce energy consumption in electrocatalytic water splitting for hydrogen production. Nevertheless, the slow rate of reaction of UOR, which entails a procedure of transferring six electrons, has hindered its widespread use. Therefore, it is crucial to design highly effective electrocatalysts for the implementation of UOR. Herein, a novel NiCo-hydroxysulfide (NiCo-HOS) electrocatalyst has been reported for UOR, which is obtained by the exchange of sulfur ions in NiCo layered double hydroxide (NiCo-LDH) nanosheets at room temperature. Benefitting from the sulfurization process, the composition, electronic structure, and surface properties of electrocatalysts have undergone significant changes and optimizations. Following sulfurization treatment, the resulting NiCo-HOS showed enhanced chemical resistance to alkaline electrolytes and improved electrical conductivity. In a 40 h operation test, it maintained high stability and provided a stable current density of 100 mA cm−2 at a relatively low potential of 1.33 V (vs. RHE) in a solution of 1 mol L−1 KOH + 0.5 mol L−1 urea. Subsequently, the anode electrolytic product is analyzed through gas chromatography (GC), and N2 is detected as the product without the presence of CO, indicating that the urea has undergone complete oxidation. [ABSTRACT FROM AUTHOR]

Urea oxidation reaction (UOR) is an ideal alternative to oxygen evolution reaction (OER) for efficient hydrogen production but is immensely plagued by slow kinetics. Herein, a multilayer hole amorphous boron‐nickel catalyst (a‐NiBx) is fabricated through a simple chemical plating method, which displays intriguing catalytic activity toward UOR, demanding a low working potential of 1.4 V to reach 100 mA cm−2. The high performance is credited to the formation of metaborate (BO2−), which can promote the formation of high‐oxidation‐state NiOOH active phase and optimize the adsorption of urea molecules. This can be confirmed by the operando spectroscopy characteristics and density functional theory calculations. Consequently, the assembled electrolyzer utilizing NiBx as bifunctional catalysts exhibited splendid catalytic activity, requiring an evidently lower voltage of 1.66 V to reach a current density of 100 mA cm−2 and 1.57 V when using Pt/C as a cathode catalyst. Moreover, the assembled electrolyzer secured a robust stability of over 200 h, as well as a four times higher hydrogen production rate than traditional water electrolysis. [ABSTRACT FROM AUTHOR]

Inhibiting the deactivation of nickel‐based catalysts caused by self‐oxidation and competitive adsorption behavior is still a major challenge for urea oxidation reaction (UOR), especially under industrial‐level current densities. In this study, a crystalline NiSe2/amorphous NiFe‐LDH (NiSe2/NiFe‐LDH) heterojunction catalyst is rationally constructed for selective electrocatalytic UOR. In situ Raman spectra and ex situ characterization results reveal that such a structure can tailor the self‐oxidation of catalyst and impede the accumulation of NiOOH species during the UOR process. Density function theory simulations disclose that the self‐driven charge transport from electron‐deficient NiFe‐LDH region to electron‐rich NiSe2 region would induce the formation of local electrophilic/nucleophilic region to adsorb the electron‐donating ‐NH2 and electron‐withdrawing C = O groups, respectively. This optimizes the adsorption of urea molecules and hinders the overaccumulation of OH− ions on the surface of NiSe2/NiFe‐LDH, which is beneficial for the priority occurrence of UOR over the oxygen evolution reaction (OER) and the realization of high UOR selectivity. Benefiting from the tailored surface self‐oxidation and favorable urea adsorption, the NiSe2/NiFe‐LDH could act as a high‐selective UOR anode and achieve ultrahigh 800 mAcm−2 only at 1.447 V. Besides, UV–vis spectrophotometry also unveiled that the NiSe2/NiFe‐LDH has the capability to electrochemically degrade urea, offering great promise for practical application potentials. [ABSTRACT FROM AUTHOR]

P-MoO 2 @CoNiP exhibits excellent HER and UOR catalytic activities. The HER performance of the catalyst can be enhanced by the leaching and reabsorption of Mo, while the UOR performance of the catalyst is improved by the reconstruction to form NiOOH. [Display omitted] • P-MoO 2 @CoNiP has a hierarchical structure of nanosheets covering the nanorods. • The abundance of active sites on P-MoO 2 @CoNiP enhances its catalytic activity. • The leaching/reabsorption of Mo improves the HER activity of P-MoO 2 @CoNiP. • Co and P incorporation boosts NiOOH formation, enhancing the activity of UOR. • P-MoO 2 @CoNiP shows efficient bifunctional catalytic activity for HER and UOR. Combining the urea oxidation reaction (UOR) with the hydrogen evolution reaction (HER) is an effective technology for energy-saving hydrogen production. Herein, a bifunctional electrocatalyst with CoNiP nanosheet coating on P-doped MoO 2 nanorods (P-MoO 2 @CoNiP) is obtained via a two-step hydrothermal followed a phosphorization process. The catalyst demonstrates exceptional alkaline HER performance due to the formation of MoO 2 and the dissolution/absorption of Mo. Meanwhile, the inclusion of Co and P in the P-MoO 2 @CoNiP catalyst facilitated the formation of NiOOH, enhancing UOR performance. Density functional theory calculations reveal that the hydrogen adsorption Gibbs free energy (ΔG H*) of P-MoO 2 @CoNiP is closer to 0 eV than CoNiP, favoring the HER. The catalyst only needs −0.08 and 1.38 V to reach 100 mA cm−2 for catalyzing the HER and UOR, respectively. The full urea electrolysis system driven by P-MoO 2 @CoNiP requires 1.51 V to achieve 100 mA cm−2, 120 mV lower than the traditional water electrolysis. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Urea plays a vital role in human society, which has various applications in organic synthesis, medicine, materials chemistry, and other fields. Conventional industrial urea production process is energy−intensive and environmentally damaging. Recently, electrosynthesis offers a greener alternative to efficient urea synthesis involving coupling CO2 and nitrogen sources at ambient conditions, which affords an achievable way for diminishing the energy consumption and CO2 emissions. Additionally, urea electrolysis, namely the electrocatalytic urea oxidation reaction (UOR), is another emerging approach very recently. When coupling with hydrogen evolution reaction, the UOR route potentially utilizes 93% less energy than water electrolysis. Although there have been many individual reviews discussing urea electrosynthesis and urea electrooxidation, there is a critical need for a comprehensive review on urea electrocatalysis. The review will serve as a valuable reference for the design of advanced electrocatalysts to enhance the electrochemical urea electrocatalysis performance. In the review, we present a thorough review on two aspects: the electrocatalytic urea synthesis and urea oxidation reaction. We summarize in turn the recently reported catalyst materials, multiple catalysis mechanisms and catalyst design principles for electrocatalytic urea synthesis and urea electrolysis. Finally, major challenges and opportunities are also proposed to inspire further development of urea electrocatalysis technology. Key Scientists: For urea electrosynthesis, Furuya et al. firstly investigated the electrochemical coreduction of CO2 and NO3−/NO2− using gas‐diffusion electrodes in 1995. Then, Wang et al. effectively achieved C—N bond formation and urea synthesis on PdCu alloy nanoparticles in 2020. Shortly, Yan and Yu et al. proposed the formation of *CO2NO2 from *NO2 and *CO2 intermediates at early stage on In(OH)3 electrocatalyst in 2021, and employed defect engineering strategy to facilitate the *CO2NH2 protonation in 2022. Amal et al. Investigated the role that Cu‐N‐C coordination plays for both the CO2RR and NO3RR. After that, Zhang's group developed In‐based electrocatalysts with artificial frustrated Lewis pairs for urea, and they offered a systematic screening approach for catalyst design in urea electrosynthesis in 2023. And sargent et al. reported a strategy that increased selectivity to urea using a hybrid catalyst. For urea electrooxidation, Stevenson et al. investigated the effect of Sr substitution toward the urea oxidation reaction. Wang et al. provided insights into the urea electrooxidation process using a β‐Ni(OH)2 electrode and Qiao et al. elucidated a two‐stage reaction pathway for UOR in 2021. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Urea plays a vital role in human society, which has various applications in organic synthesis, medicine, materials chemistry, and other fields. Conventional industrial urea production process is energy−intensive and environmentally damaging. Recently, electrosynthesis offers a greener alternative to efficient urea synthesis involving coupling CO2 and nitrogen sources at ambient conditions, which affords an achievable way for diminishing the energy consumption and CO2 emissions. Additionally, urea electrolysis, namely the electrocatalytic urea oxidation reaction (UOR), is another emerging approach very recently. When coupling with hydrogen evolution reaction, the UOR route potentially utilizes 93% less energy than water electrolysis. Although there have been many individual reviews discussing urea electrosynthesis and urea electrooxidation, there is a critical need for a comprehensive review on urea electrocatalysis. The review will serve as a valuable reference for the design of advanced electrocatalysts to enhance the electrochemical urea electrocatalysis performance. In the review, we present a thorough review on two aspects: the electrocatalytic urea synthesis and urea oxidation reaction. We summarize in turn the recently reported catalyst materials, multiple catalysis mechanisms and catalyst design principles for electrocatalytic urea synthesis and urea electrolysis. Finally, major challenges and opportunities are also proposed to inspire further development of urea electrocatalysis technology. Key Scientists: For urea electrosynthesis, Furuya et al. firstly investigated the electrochemical coreduction of CO2 and NO3−/NO2− using gas‐diffusion electrodes in 1995. Then, Wang et al. effectively achieved C—N bond formation and urea synthesis on PdCu alloy nanoparticles in 2020. Shortly, Yan and Yu et al. proposed the formation of *CO2NO2 from *NO2 and *CO2 intermediates at early stage on In(OH)3 electrocatalyst in 2021, and employed defect engineering strategy to facilitate the *CO2NH2 protonation in 2022. Amal et al. Investigated the role that Cu‐N‐C coordination plays for both the CO2RR and NO3RR. After that, Zhang's group developed In‐based electrocatalysts with artificial frustrated Lewis pairs for urea, and they offered a systematic screening approach for catalyst design in urea electrosynthesis in 2023. And sargent et al. reported a strategy that increased selectivity to urea using a hybrid catalyst. For urea electrooxidation, Stevenson et al. investigated the effect of Sr substitution toward the urea oxidation reaction. Wang et al. provided insights into the urea electrooxidation process using a β‐Ni(OH)2 electrode and Qiao et al. elucidated a two‐stage reaction pathway for UOR in 2021. [ABSTRACT FROM AUTHOR]

Electrochemical urea oxidation reaction (UOR) offers a promising alternative to the oxygen evolution reaction (OER) in clean energy conversion and storage systems. Nickel‐based catalysts are regarded as highly promising electrocatalysts for the UOR. However, their effectiveness is significantly hindered by the unavoidable self‐oxidation reaction of nickel species during UOR. To address this challenge, we proposed an interface chemistry modulation strategy to boost UOR kinetics by creating a high‐energy interfacial heterostructure. This heterostructure incorporates Ag at the CoOOH@NiOOH heterojunction interface, where strong interactions significantly promote the electron exchanges at the heterojunction interface between ‐OH and ‐O groups. Consequently, the improved electron delocalization leads to the formation of stronger bonds between Co sites and urea CO(NH2)2, promoting a preference for urea to occupy Co active sites over OH*. The resulting catalyst, Ag−CoOOH@NiOOH, demonstrates ultrahigh UOR activity with a low potential of 1.33 V at 100 mA cm−2. The fabricated catalyst exhibits a mass activity over 11.9 times greater than the initial cobalt oxyhydroxide. The rechargeable urea‐assisted zinc‐air batteries (ZABs) achieve a record‐breaking energy efficiency of 74.56 % at 1 mA cm−2, remarkable durability (1000 hours at a current density of 50 mA cm−2), and quick charge performances. [ABSTRACT FROM AUTHOR]

In contrast to the thermodynamically unfavorable anodic oxygen evolution reaction, the electrocatalytic urea oxidation reaction (UOR) presents a more favorable thermodynamic potential. However, the practical application of UOR has been hindered by sluggish kinetics. In this study, hierarchical porous nanosheet arrays featuring abundant Ni‐WO3 heterointerfaces on nickel foam (Ni‐WO3/NF) is introduced as a monolith electrode, demonstrating exceptional activity and stability toward UOR. The Ni‐WO3/NF catalyst exhibits unprecedentedly rapid UOR kinetics (200 mA cm−2 at 1.384 V vs. RHE) and a high turnover frequency (0.456 s−1), surpassing most previously reported Ni‐based catalysts, with negligible activity decay observed during a durability test lasting 150 h. Ex situ X‐ray photoelectron spectroscopy and density functional theory calculations elucidate that the WO3 interface significantly modulates the local charge distribution of Ni species, facilitating the generation of Ni3+ with optimal affinity for interacting with urea molecules and CO2 intermediates at heterointerfaces during UOR. This mechanism accelerates the interfacial electrocatalytic kinetics. Additionally, in situ Fourier transform infrared spectroscopy provides deep insights into the substantial contribution of interfacial Ni‐WO3 sites to UOR electrocatalysis, unraveling the underlying molecular‐level mechanisms. Finally, the study explores the application of a direct urea fuel cell to inspire future practical implementations. [ABSTRACT FROM AUTHOR]

The urea oxidation reaction (UOR) has attracted much attention as an efficient alternative reaction to oxygen evolution reaction (OER) due to its low required overpotential. Despite significant progress in efficient nickel‐based catalysts, the fundamental issues regarding product selectivity control and dissociation mechanism during the UOR process have not been clarified. Here, we report that tuning the electron delocalization strength of Ni sites significantly affects the OH− binding sites, altering urea molecule dissociation patterns in alkaline systems. Using spinel NiCo2O4 as a model catalyst, the charge delocalization strength of nickel active centers is influenced by the degree of phosphorus‐substituted anions. Specifically, complete phosphorus‐substituted spinel enhances N2 selectivity up to 26.8 % with a peak current density of 300 mA ⋅ cm−2, while partial phosphorus‐substituted spinel achieves a Faraday efficiency of 78.1 % for liquid products (NOx−). Experiments and theory reveal that strong charge delocalization at Ni sites favors remote‐site attack on urea molecules by hydroxide ions, whereas weak delocalization prefers nearby‐site attack, enhancing UOR efficiency and suppressing OER in both pathways. [ABSTRACT FROM AUTHOR]