Remarkable hydrogen evolution reaction (HER) or superior oxygen evolution reaction (OER) catalyst has been applied in water splitting, however, utilizing a bifunctional catalyst for simultaneously generating H2 and O2 is still a challenging issue, which is crucial for improving the overall efficiency of water electrolysis. Herein, inspired by the superiority of carbon conductivity, the propitious H atom binding energy of metallic cobalt, and better OER activity of cobalt oxide, we synthesized cobalt-cobalt oxide/N-doped carbon hybrids (CoOx@CN) composed of Co(0), CoO, Co3O4 applied to HER and OER by simple one-pot thermal treatment method. CoOx@CN exhibited a small onset potential of 85 mV, low charge-transfer resistance (41 Ω), and considerable stability for HER. Electrocatalytic experiments further indicated the better performance of CoOx@CN for HER can be attributed to the high conductivity of carbon, the synergistic effect of metallic cobalt and cobalt oxide, the stability of carbon-encapsulated Co nanoparticles, and the introduction of electron-rich nitrogen. In addition, when used as catalysts of OER, the CoOx@CN hybrids required 0.26 V overpotential for a current density of 10 mA cm(-2), which is comparable even superior to many other non-noble metal catalysts. More importantly, an alkaline electrolyzer that approached ∼20 mA cm(-2) at a voltage of 1.55 V was fabricated by applying CoOx@CN as cathode and anode electrocatalyst, which opened new possibilities for exploring overall water splitting catalysts.

Highly uniform ruthenium (Ru) nanoparticles over N-doped carbon (Ru@CN) was designed and confirmed as a promising candidate for the hydrogen evolution reaction (HER) over a wide pH range.

The earth-abundant nanohybrids Co 0 /Co 3 O 4 @N-doped carbon nanotubes were fabricated via an efficient thermal condensation of D-glucosamine hydrochloride, melamine and Co(NO 3 ) 2 ·6H 2 O. The hybrids furnish excellent catalytic activity and perfect chemoselectivity (>99%) for a wide range of substituted nitroarenes (21 examples) under relatively mild conditions. The high catalytic performance and durability is attributed to the synergistic effects between each component, the unique structure of graphene layers-coated Co 0 and the electronic activation of doped nitrogen. Density functional calculations indicate that the inner Co 0 core and N species on the carbon shell can significantly decrease the dissociation energies of H 2 , giving evidence of the ability of carbon shell in the hybrids to H 2 activation. These results open up an avenue to design more powerful low-cost catalysts for industrial applications.

RuPd alloy nanoparticles (3.6 nm) uniformly dispersed on N-doped carbon (RuPd/CN) was prepared via a simple ultrasoundassisted coreduction method. The RuPd/CN is highly active, selective, and stable in the hydrogenation of benzoic acid to cyclohexanecarboxylic acid under mild conditions with a TOF up to 2066 h −1 . It was found that the bimetallic RuPd/CN catalyst exhibited a substantially enhanced activity in comparison with the monometallic catalysts (Ru/CN and Pd/CN). The reason for the higher performance of the RuPd/CN catalyst is considered to be the increased Ru 0 /Ru n+ ratio induced by the electronic interaction between Ru and Pd, as evidenced by various characterizations. Notably, the different phenomenon of activity platform on different catalysts ascribed to the effect of hydrogen pressure was newly observed and further explained by first-principle studies. Moreover, the factors influencing the adsorption modes of BA, especially the configuration of the carboxyl group, have been investigated preliminarily in first-principle studies, giving a distinct insight from the former work. The reason the carboxyl group in benzoic acid does not undergo hydrogenation, which results in superior selectivity (>99%), is also revealed by a comparison of the thermodynamics of hydrogenation and dissociation of the carboxyl group.

Paired electrosynthesis is a promising technology with the potential to generate value-added products at both electrodes in a cost-effective manner. Herein, 3D vanadium nitride (VN) and Pd/VN hollow nanospheres are successfully fabricated and coupled to carry out simultaneous electrocatalytic oxidation (ECO) and electrocatalytic hydrogenation (ECH) of 5-hydroxymethylfurfural (HMF) into 2, 5-furandicarboxylic acid (FDCA) and 2,5-bishydroxymethyl-tetrahydrofuran (DHMTHF), respectively. VN shows excellent ECO performance with high HMF conversion (≥98%), FDCA selectivity (≥96%), and faradaic efficiency (≥84%) after a stability test, and Pd/VN achieves high ECH selectivity for DHMTHF at ≥88% and an HMF conversion of ≥90%, with a faradaic efficiency of ≥86%. VN and Pd/VN incorporated into a membrane electrode assembly in a paired electrolysis system shows potential for large-scale biomass conversion and upgrading. Theoretical calculations reveal that the higher performance of VN for the production of ECO can be attributed to its lower d-band center level relative to the Fermi level compared to that of V 2 O 5 , which favors HMF chemisorption and activation. This study paves the way for developing paired electrosynthesis technologies with the potential for biomass utilization and energy conversion.

The research of a robust catalytic system based on single NiO electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiO-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiO@bamboo-like carbon nanotube hybrids (NiO@BCNTs) is designed. The hybrids exhibit superb catalytic ability and considerable durability in alkaline solution. A benchmark HER current density of 10 mA cm has been achieved at an overpotential of ∼79 mV. In combination with the experimental results and density functional theory (DFT) calculations, this for the first time definitely validates that the inherent high Ni ratio and the Ni on the interface of Ni/NiO play a vital role in the outstanding catalytic performance. Especially, the Ni on the interface of Ni/NiO performs superior activity for water splitting compared with that of bulk Ni. These conclusions provide guidance for the rational design of the future non-noble metallic catalysts.

Electrocatalytic water splitting for hydrogen production is an appealing way to reduce carbon emissions and generate renewable fuels. This promising process, however, is limited by its sluggish reaction kinetics and high‐cost catalysts. Construction of low‐cost and high‐performance non‐noble metal‐based catalysts have been one of the most effective approaches to address these grand challenges. Notably, the electronic structure tuning strategy, which could subtly tailor the electronic states, band structures, and adsorption ability of the catalysts, has become a pivotal way to further enhance the electrochemical water splitting reactions based on non‐noble metal‐based catalysts. Particularly, heteroatom‐doping plays an effective role in regulating the electronic structure and optimizing the intrinsic activity of the catalysts. Nevertheless, the reaction kinetics, and in particular, the functional mechanisms of the hetero‐dopants in catalysts yet remains ambiguous. Herein, the recent progress is comprehensively reviewed in heteroatom doped non‐noble metal‐based electrocatalysts for hydrogen evolution reaction, particularly focus on the electronic tuning effect of hetero‐dopants in the catalysts and the corresponding synthetic pathway, catalytic performance, and activity origin. This review also attempts to establish an intrinsic correlation between the localized electronic structures and the catalytic properties, so as to provide a good reference for developing advanced low‐cost catalysts.

The electron transfer from TiO2-VO to Pd NPs plays a crucial role in promoting ORR performance of Pd-based electrocatalysts.