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Reasonable design of Pd-based catalysts with specific composition and morphology is of great importance for promoting the commercial application. of direct alcohol fuel cells (DAFCs). Recently, two-dimension (2D) with high density of defects and massive low-coordinated surface atom has become research highlights in the field of catalysis. Herein, we report a wet chemical method for synthesizing PdCu nanosheets with abundant wrinkles. The ultrathin two-dimensional structure endows catalysts plentiful catalytic active sites and large specific surface area, improving atomic utilization efficiency. The formation of bimetallic PdCu alloy structure leads to the adjustment of Pd electronic structure, resulting in lattice compression effect. Benefitting from the structural and compositional characteristics, PdCu nanosheets (NSs) exhibits excellent electrocatalytic performance for ethylene glycol oxidation reaction (EGOR) and glycerol oxidation reaction (GOR) with the mass activity of 7031 mA mg−1/5117 mA mg−1, which is 4.4/3.9 times higher than that of commercial Pd/C catalysts. Furthermore, the remained mass activity of PdCu NSs is 3991/3851 mA mg−1 after the durability measurement for EGOR/GOR, which confirm PdCu NSs possesses superior stability. We believe that our synthetic strategy could provide robust reference for the development of high-performance eletrocatalysts. [Display omitted] • PdCu nanosheets were prepared by a facile solvothermal method. • The PdCu NSs provide ideal electrocatalytic active sites. • The PdCu NSs exhibited excellent electrocatalytic performance toward EGOR and GOR. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of open-structured amorphous/crystalline CoNiRuO x heterointerface nanocages are prepared by a simple method. • The suitable crystallinity and defects levels could be simultaneously precise regulated. • The optimized CoNiRuO x -2 PNCs exhibited the superior OER activity with an overpotential of 245 mV at 10 mA cm−2. Amorphous/crystalline (a/c) metal-oxide nanocages with defects are promising materials towards the realization of efficient water electrocatalysis. In this work, we not only constructed a Ru doping porous nanocages (PNCs) structure, but also studied the relationship between both crystallinity of a/c degrees and oxygen vacancy (O vac) levels in a/c CoNiRuO x PNCs catalysts and their catalytic properties. Owing to the rich mass transfer channels, optimized crystallinity and O vac levels, and efficient catalytic model of "Ni-O-Co-O-Ru-O-Ni" for well-distributed electron density, the optimized CoNiRuO x -2 PNCs exhibited the alkaline oxygen evolution reaction (OER) properties with an overpotential of 245 mV at 10 mA cm−2 and remarkable stability for 60 h, surpassing other series of a/c CoNiRuO x and benchmark RuO 2 catalysts. In addition, the electrode couple a/c CoNiRuO x -2//Pt/C only need an ultralow voltage of 1.54 V to drive overall water splitting. This work proposed the introduction and quantitative control on both a/c heterostructure degree and O vac level, offering guidelines for OER catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amorphization/crystallization methods of TM-based catalysts are summarized. • Various kinds of a/c TM-based catalysts are reviewed. • Perspectives and challenges of a/c TM-based catalysts for water splitting are outlined. The rational phase engineering on transition-metal-based (TM-based) catalysts is an efficient strategy to improve the catalytic performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in water splitting. Combining high conductivity from crystalline phase with orderly atomic arrangement and high activity from amorphous phase with abundant unsaturated sites, more amorphous/crystalline (a/c) heterostructure TM-based catalysts with optimized electronic structures have been confirmed to exhibit superior OER and HER properties with well-balanced activity and stability. However, the rational design of the a/c TM-based catalysts for water splitting is often ignored. In this review, we firstly summarized the amorphization/crystallization strategies for constructing a/c TM-based catalysts including pyrolysis method, composition-tuned approach, electrochemical method, chemical etching and other strategies. Then, we introduced various kinds of a/c TM-based catalysts such as a/c TM-based alloys, oxides and hydroxides, nitrides/phosphides/sulfides, and composites. In addition, the roles of a/c interfaces on the performance promotion for OER and HER have been analyzed, which involved the active sites increasement with optimized d-band center, catalytic kinetics acceleration with fast electron transfer, and stability enhancement with electron density redistribution. Finally, we proposed the existing challenges and further perspectives referring to the precise synthesis, in-depth activity investigation and performance promotion. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MOF-derived CoNiFeP nanospindles catalysts are prepared by a facile ion-exchange and phosphorization method. • The CoNiFeP with unique yolk-shell structure exhibit rich channels for mass transportation. • The construction of robust phosphide heterojunction interface in CoNiFeP boost the electron transfer. • The promotion mechanism of OER property is analyzed on CoNiFeP with well-tuned composition. The heterogeneous interface engineering of nanocatalysts has been proved as an efficient strategy to promote the oxygen evolution reaction (OER) catalytic performance. Different from the conventional hollow structures, the yolk-shell construction could defend the distortion and dissolution during OER for stability improvement. However, it is still a great challenging to simultaneously construct heterogeneous interface and yolk-shell structure based on electrocatalysts with well-tuned composition and structure. Herein, we developed a facile synthetic method to prepare the yolk-shell trimetallic phosphide catalysts by starting with MIL-88A nanospindles templates. Benefitting from heterogeneous interface with fast electron transfer, yolk-shell architecture with rich channels for mass transportation, and active metal doping with electron structure modulation, the obtained CoNiFeP yolk-shell nanospindles (YSNSs) catalysts displayed superior OER catalytic properties with the overpotential of only 261 mV to deliver a current density of 10 mA cm−2 in alkaline media. Furthermore, the yolk-shell architecture endowed CoNiFeP with remarkable OER stability for 60 h. By coupling CoNiFeP with Pt/C electrodes to drive overall water splitting, an ultralow cell voltage of 1.56 V is required. The experimental and mechanistic studies indicated the optimized binding energy of *OOH ad and *OH ad intermediates by constructing robust phosphide interface. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MOF mediated method has been proposed for the synthesis of (Ru-Co)O x nanobox. • The (Ru-Co)O x nanoboxes are endowed with rich vacancies and interfaces. • The doping of ultralow Ru effectively modifies the electronic structure of CoO x. • (Ru-Co)O x nanoboxes could deliver outstanding electrocatalytic OER performance. For accelerating the reaction kinetics of oxygen evolution reaction (OER) and improving the efficiency of water electrolysis, it is essential to develop high-performance and robust OER electrocatalysts. Herein, heterostructured ruthenium-cobalt oxide hollow nanoboxes are developed for enabling a highly efficient OER electrocatalysis. Benefitting from the desirable structural and compositional merits of more exposure of surface active centers, modulated electronic structure, and interfacial synergy effect, the (Ru-Co)O x hollow nanobox could exhibit excellent electrocatalytic performance toward OER. Particularly, an extremely low overpotential of 265 mV is necessary for the optimized (Ru-Co)O x -350 to achieve a current density of 10 mA cm−2, together with a small Tafel slope of 60 mV dec-1. More interestingly, by combing (Ru-Co)O x -350 with Pt/C for driving alkaline water splitting, an ultralow cell voltage of merely 1.57 V is required. [ABSTRACT FROM AUTHOR]