Interface Enables Faster Surface Reconstruction in a Heterostructured CuSey/NiSex Electrocatalyst for Realizing Urea Oxidation.

Creating affordable electrocatalysts and understanding the real-time catalytic process of the urea oxidation reaction (UOR) are crucial for advancing urea-based technologies. Herein, a Cu-Ni based selenide electrocatalyst (CuSey/NiSex/NF) was created using a hydrothermal technique and selenization treatment, featuring a heterogeneous interface rich in Cu2-xSe, Cu3Se2, Ni3Se4, and NiSe2. This catalyst demonstrated outstanding urea electrooxidation performance, achieving 10 mA cm-2 with just 1.31 V and sustaining stability for 96 h. Through in-situ Raman spectroscopy and ex-situ characterizations, it is discovered that NiOOH is formed through surface reconstruction in the UOR process, with high-valence Ni serving as the key site for effective urea oxidation. Moreover, the electrochemical analysis revealed that CuSey had dual effects. An analysis of XPS and electrochemical tests revealed that electron transfer from CuSey to NiSex within the CuSey/NiSex/NF heterostructure enhanced the UOR kinetics of the catalyst. Additionally, according to the in-situ Raman spectroscopy findings, the existence of CuSey facilitates a easier and faster surface reconstruction of NiSex, leading to the creation of additional active sites for urea oxidation. More significantly, this work provides an excellent "precatalyst" for highly efficient UOR, along with an in-depth understanding of the mechanism behind the structural changes in electrocatalysts and the discovery of their true active sites.

Electron regulation of CeO2 on CoP multi-shell hetero-junction micro-sphere towards highly efficient water oxidation.

CeO2 has been identified as a significant cocatalyst to enhance the electrocatalytic activity of transition metal phosphides (TMPs). However, the electrocatalytic mechanism by which CeO2 enhances the catalytic activity of TMP remains unclear. In this study, we have successfully developed a unique CeO2-CoP-1-4 multishell microsphere heterostructure catalyst through a simple hydrothermal and calcination process. CeO2-CoP-1-4 exhibits great potential for electrocatalytic oxygen evolution reaction (OER), requiring only an overpotential of 254 mV to achieve a current density of 10 mA cm-2. Moreover, CeO2-CoP-1-4 demonstrates excellent operating durability lasting for 55 h. The presence of CeO2 as a cocatalyst can regulate the microsphere structure of CoP, the resulting multishell microsphere structure can shorten the mass transfer distance, and improve the utilization rate of the active site. Furthermore, in situ Raman and ex situ characterizations, and DFT theoretical calculation results reveal that CeO2 can effectively regulates the electronic structure of Co species, reduces the reaction free energy of rate-limiting step, thus increase the reaction kinetic. Overall, this study provides experimental and theoretical evidence to better comprehend the mechanism and structure evolution of CeO2 in enhancing the OER performance of CoP, offering a unique design inspiration for the development of efficient hollow heterojunction electrocatalysts.

Dehydrogenation of Ammonia Borane by Platinum-Nickel Dimers: Regulation of Heteroatom Interspace Boosts Bifunctional Synergetic Catalysis.

Regulation of the atom-atom interspaces of dual-atom catalysts is essential to optimize the dual-atom synergy to achieve high activity but remains challenging. Herein, we report an effective strategy to regulate the Pt1 -Ni1 interspace to achieve Pt1 Ni1 dimers and Pt1 +Ni1 heteronuclear dual-single-atom catalysts (HDSACs) by tailoring steric hindrance between metal precursors during synthesis. Spectroscopic characterization reveals obvious electron transfers in Pt1 Ni1 oxo dimers but not in Pt1 +Ni1 HDSAC. In the hydrolysis of ammonia borane (AB), the H2 formation rates show an inverse proportion to the Pt1 -Ni1 interspace. The rate of Pt1 Ni1 dimers is ≈13 and 2 times higher than those of Pt1 and Pt1 +Ni1 HDSAC, manifesting the interspace-dependent synergy. Theoretical calculations reveal that the bridging OH group in Pt1 Ni1 dimers promotes water dissociation, while Pt1 facilitates the cleavage of B-H bonds in AB, which boosts a bifunctional synergy to accelerate H2 production cooperatively.

Hydrolysis of Ammonia Borane on a Single Pt Atom Supported by N-Doped Graphene.

The hydrolysis of ammonia borane (NH3BH3 or AB) at room temperature is a promising method to produce hydrogen, but the complete reaction mechanism is still less investigated. Herein, the full hydrolysis process of the AB molecule on single Pt atom coordinated by two carbon atoms and one nitrogen atom (Pt1-C2N1) on nitrogen doped graphene is investigated using the density functional theory (DFT) method. Our results demonstrate that the rate-limiting step is the formation of *BH2NH3 by breaking the first B-H bond in AB with an energy barrier of 0.68 eV, implying that Pt1-C2N1 is a potential room-temperature catalyst for the full hydrolysis of AB. In addition, 27 more types of M1-C2N1 (M represents transiton metal atom) and Pt1 supported on nitrogen-doped graphene with different local coordination environments (Pt1-CxNy, x and y are the number of carbon and nitrogen atoms that coordinated with the platinum atom) are considered to screen out potential single-atom catalysts for AB hydrolysis. The screening results further show that Pt1-C1N2 is another potential catalyst for AB hydrolysis. In particular, two hydrogen atoms precovered on Pt1-C1N2, resulting in a lower energy barrier for the rate-limiting step than that on Pt1-C2N1. This study provides a prototype of Pt1-C1N2 and Pt1-C2N1 for catalytic full hydrolysis of AB at room temperature.

An Efficient Strategy toward Multichambered Carbon Nanoboxes with Multiple Spatial Confinement for Advanced Sodium-Sulfur Batteries.

Intricate hollow carbon structures possess vital function for anchoring polysulfides and enhancing the utilization of sulfur in room-temperature sodium-sulfur batteries. However, their synthesis is extremely challenging due to the complex structure. Here, a facile and efficient strategy is developed for the controllable synthesis of N/O-doped multichambered carbon nanoboxes (MCCBs) by selective etching and stepwise carbonization of ZIF-8 nanocubes. The MCCBs consist of porous carbon shells on the outside and connected carbon grids with a hollow structure on the inside, bringing about a MCCBs structure. As a sulfur host, the multichambered structure has better spatial encapsulation and integrated conductivity via the inner interconnected carbon grids, which combines the characteristics of short charge transfer path and superb physicochemical adsorption along with mechanical strength. As expected, the S@MCCBs cathode realizes decent cycle stability (0.045% capacity decay per cycle over 800 cycles at 5 A g-1) and enhanced rate performance (328 mA h g-1 at 10 A g-1). Furthermore, in situ transmission electron microscopy (TEM) observation confirms the good structural stability of the S@MCCBs during the (de)sodiation process. Our work demonstrates an effective strategy for the rational design and accurate construction of intricate hollow materials for high-performance energy storage systems.

Prediction of an Al4C4 superatom organic framework (SOF) material based on the superatom network model.

Metal organic framework (MOF) materials have attracted significant attention due to their wide potential applications, but it is still a challenge to design MOFs with advanced properties by exploring novel metal nodes. In this study, a kind of superatom organic framework (SOF) material is proposed based on the superatom network (SAN) model. Tetrahedron Al4 superatom unit is used as nodes in the MOF structure, and linear -CC- ligands are chosen as linkers. Localized chemical bonding analysis and nucleus-independent chemical shift (NICS) scan confirm that the Al4 core keeps the superatom electronic shell in the SOF structure. Further calculations demonstrate that this Al4C4 crystal has high dynamic and thermal stabilities, with an indirect semiconductor band gap of 2.57 eV. Analysis of its optical properties indicates its potential applications as an optoelectronic device. This novel kind of SOF material has both porous framework as traditional MOFs and superatomic character in its nodes, indicating its unique potential properties. Our work would provide a new way for designing functional MOF materials.

Hydrogenation of Furfural to Cyclopentanone under Mild Conditions by a Structure-Optimized Ni-NiO/TiO2 Heterojunction Catalyst.

The catalytic conversion of biomass-derived furfural (FFA) into cyclopentanone (CPO) in aqueous solution is an important pathway to obtain sustainable resources. However, the conversion and selectivity under mild conditions are still unsatisfactory. In this study, a catalyst consisting of Ni-NiO heterojunction supported on TiO2 with optimized composition of anatase and rutile (Ni-NiO/TiO2 -Re450) is prepared by pyrolysis at 450 °C. With Ni-NiO/TiO2 -Re450, as catalyst, complete conversion of FFA and 87.4 % yield of CPO are achieved under mild reaction conditions (1 MPa, 140 °C, 6 h). 95.4 % FFA conversion is retained up to the fifth run, indicating the high stability of the catalyst. Multiple characterizations, control experiments, and theoretical calculations demonstrate that the good catalytic performance of Ni-NiO/TiO2 -Re450 can be attributed to a synergistic effect of the Ni-NiO heterojunction and the TiO2 support. This low-cost catalyst may expedite the catalytic upgrading and practical application of biomass-derived chemicals.