Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges, particularly for the construction of hydrogen evolution reaction (HER) catalysts operating at ampere-level current density. Herein, the unique Ru and RuP₂ dual nano-islands are deliberately implanted on N-doped carbon substrate (denoted as Ru-RuP₂/NC), in which a built-in electric field (BEF) is spontaneously generated between Ru-RuP₂ dual nano-islands driven by their work function difference. Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP₂ dual nano-islands, which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density, and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP₂ nano-islands through hydrogen spillover process. As a result, the Ru-RuP₂/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm⁻² along with the superior stability over 1000 h, holding the great promising prospect in practical applications at ampere-level current density. More importantly, this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process, which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density.

Cathode interfacial materials (CIMs) stand as critical elemental in organic solar cells (OSCs), which can align energy levels, and foster ohmic contacts between the cathode and active layer of the OSCs. Nevertheless, the lagging advancement in CIMs has concurrently engendered the oversight of theoretical inquiries pertaining to the impact of molecular structure on their performance. Delving into this realm, we present two propeller-shaped isomers, 4,4',4''-(benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-triyl)tris(2-(3-(dimethylamino)propyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) (3ONIN) and 6,6',6''-(benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-triyl)tris(2-(3-(dimethylamino)propyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) (3PNIN), distinguished by their molecular planarity, as a promising foundation for crafting highly efficient OSCs. This study illuminates the superiority of 3PNIN with more plane structure, exemplified by its enhanced molar extinction coefficient, deeper lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels, intensified self-doping effect, heightened electron mobility, and elevated conductivity, in comparison to its counterpart, 3ONIN. As a result, 3PNIN and 3ONIN-treated OSC devices yield efficiencies of 17.73% and 16.82%, respectively. This finding serves as a compelling validation of the critical role played by molecular planarity in influencing CIM performance.

Single-atom catalysts (SACs) have received considerable attention in hydrogenation of nitroaromatic compounds to aromatic amines. In order to enhance the exposure of single atoms and overcome the mass transfer limitation, construction of hierarchical porous supports for single atoms is highly desirable. Herein, we report a straightforward method to synthesize Co single-atoms supported on a hollow-on-hollow structured carbon monolith (Co₁/HOHC-M) by pyrolysis of α-cellulose monolith loaded with PS-core@ZnCo-zeolite imidazolate frameworks-shell nanospheres (PS@Zn-ZIFs/α-cellulose). The hollow-on-hollow structure consists of a large hollow void with a diameter of ~ 290 nm (derived from the decomposition of polystyrene (PS) nanospheres) and a thin shell with hollow spherical pores with a diameter of ~ 10 nm (derived from the evaporation of ZnO nanoparticles that are in-situ formed during pyrolysis in the presence of CO₂ from α-cellulose decomposition). Benefitting from the hierarchically porous architecture, the Co₁/HOHC-M exhibits excellent catalytic performance (reaction rate of 421.6 mmol·g_Co⁻¹·h⁻¹) in the transfer hydrogenation of nitrobenzene to aniline, outperforming the powdered sample of Co₁/HCS without the hollow spherical mesopores (reaction rate of 353.8 mmol·g_Co⁻¹·h⁻¹). It is expected that this strategy could be well extended in heterogeneous catalysis, given the wide applications of porous carbon-supported single-atom catalysts.

Oxygen reduction reaction (ORR) plays an important role in the next-generation energy storage technologies, whereas it involves the sluggish and complicated proton-coupled electron transfer (PCET) steps that greatly limit the ORR kinetics. Therefore, it is urgent to construct an efficient catalyst that could simultaneously achieve the rapid oxygen-containing intermediates conversion and fast PCET process but remain challenging. Herein, the adjacent Fe₃C nanoparticles coupling with single Fe sites on the bubble-wrap-like porous N-doped carbon (Fe₃C@Fe_SA-NC) were deliberately constructed. Theoretical investigations reveal that the adjacent Fe₃C nanoparticles speed up the water dissociation and serve as proton-feeding centers for boosting the ORR kinetics of single Fe sites. Benefiting from the synergistic effect of the Fe₃C and single Fe sites, the Fe₃C@Fe_SA-NC affords an excellent half-wave potential of 0.88 V, and enables the assembled Zn-air batteries with the high peak power density of 164.5 mW·cm⁻² and long-term stability of over 200 h at high current densities at 50 mA·cm⁻². This work clarifies the mechanism for improving ORR kinetics of single atomic sites by engineering the adjacent proton-feeding centers, shedding light on the rational design of cost-effective electrocatalysts for energy conversion and storage technologies.

Deliberate modulation of the electronic structure via interface engineering is one of promising perspectives to build advanced catalysts for urea oxidation reaction (UOR) at high current densities. However, it still remains some challenges originating from the intrinsically sluggish UOR dynamics and the high energy barrier for urea adsorption. In response, we report the coupled NiSe₂ nanowrinkles with Ni₅P₄ nanorods heterogeneous structure onto Ni foam (denoted as NiSe₂@Ni₅P₄/NF) through successive phosphorization and selenization strategy, in which the produced closely contacted interface could provide high-flux electron transfer pathways. Theoretical findings decipher that the fast charge transfer takes place at the interfacial region from Ni₅P₄ to NiSe₂, which is conducive to optimizing adsorption energy of urea molecules. As expected, the well-designed NiSe₂@Ni₅P₄/NF only requires the low potential of 1.402 V at the current density of 500 mA·cm⁻². More importantly, a small Tafel slope of 27.6 mV·dec⁻¹, a high turnover frequency (TOF) value of 1.037 s⁻¹ as well as the prolonged stability of 950 h at the current density of 100 mA·cm⁻² are also achieved. This study enriches the understanding on the electronic structure modulation via interface engineering and offers bright prospect to design advanced UOR catalysts.

Interface engineering has gradually attracted substantial research interest in constructing active bifunctional catalysts toward urea electrolysis. The fundamental understanding of the crystallinity transition of the components on both sides of the interface is extremely significant for realizing controllable construction of catalysts through interface engineering, but it still remains a challenge. Herein, the Ni/NiO heterogenous nanoparticles are successfully fabricated on the porous N-doped carbon spheres by a facile hydrothermal and subsequent pyrolysis strategy. And for the first time we show the experimental observation that the Ni/NiO interface can be fine-tuned via simply tailoring the heating rate during pyrolysis process, in which the crystalline/amorphous or crystalline/crystalline Ni/NiO heterostructure is deliberately constructed on the porous N-doped carbon spheres (named as CA-Ni/NiO@NCS or CC-Ni/NiO@NCS, respectively). By taking advantage of the unique porous architecture and the synergistic effect between crystalline Ni and amorphous NiO, the well-designed CA-Ni/NiO@NCS displays more remarkable urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) activity than its crystalline/crystalline counterpart of CC-Ni/NiO@NCS. Particularly, the whole assembled two-electrode electrolytic cell using the elaborate CA-Ni/NiO@NCS both as the anode and cathode can realize the current density of 10 mA·cm⁻² at a super low voltage of 1.475 V (264 mV less than that of pure water electrolysis), as well as remarkable prolonged stability over 63 h. Besides, the H₂ evolution driven by an AA battery and a commercial solar cell is also studied to enlighten practical applications for the future.