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Electrocatalytic CO2 reduction is a typical reaction involving two reactants (CO2 and H2O). However, the role of H2O dissociation, which provides active *H species to multiple protonation steps, is usually overlooked. Herein, we construct a dual-active sites catalyst comprising atomic Cu sites and Cu nanoparticles supported on N-doped carbon matrix. Efficient electrosynthesis of multi-carbon products is achieved with Faradaic efficiency approaching 75.4% with a partial current density of 289.2 mA cm−2 at −0.6 V. Experimental and theoretical studies reveal that Cu nanoparticles facilitate the C-C coupling step through *CHO dimerization, while the atomic Cu sites boost H2O dissociation to form *H. The generated *H migrate to Cu nanoparticles and modulate the *H coverage on Cu NPs, and thus promote *CO-to-*CHO. The dual-active sites effect of Cu single-sites and Cu nanoparticles gives rise to the catalytic performance. A dual-site catalyst consisting of Cu nanoparticles (NPs) and atomic Cu sites is designed. The atomic Cu boosts H2O dissociation for modulating the *H coverage on Cu NPs, improving the efficiency of CO2 electroreduction to multi-carbon products. [ABSTRACT FROM AUTHOR]

A dual‐site catalyst allows for a synergetic reaction in the close proximity to enhance catalysis. It is highly desirable to create dual‐site interfaces in single‐atom system to maximize the effect. Herein, we report a cation‐deficient electrostatic anchorage route to fabricate an atomically dispersed platinum–titania catalyst (Pt1O1/Ti1−xO2), which shows greatly enhanced hydrogen evolution activity, surpassing that of the commercial Pt/C catalyst in mass by a factor of 53.2. Operando techniques and density functional calculations reveal that Pt1O1/Ti1−xO2 experiences a Pt−O dual‐site catalytic pathway, where the inherent charge transfer within the dual sites encourages the jointly coupling protons and plays the key role during the Volmer–Tafel process. There is almost no decay in the activity of Pt1O1/Ti1−xO2 over 300 000 cycles, meaning 30 times of enhancement in stability compared to the commercial Pt/C catalysts (10 000 cycles). [ABSTRACT FROM AUTHOR]

Single‐atom catalysts have attracted much attention. Reported herein is that regulating charge transfer of lattice oxygen atoms in serial single‐atom‐doped titania enables tunable hydrogen evolution reaction (HER) activity. First‐principles calculations disclose that the activity of lattice oxygen for the HER can be regularly promoted by substituting its nearest metal atom, and doping‐induced charge transfer plays an essential role. Besides, the realm of the charge transfer of the active site can be enlarged to the second nearest atom by creating oxygen vacancies, resulting in further optimization for the HER. Various single‐atom‐doped titania nanosheets were fabricated to validate the proposed model. Taking advantage of the localized charge transfer to the lattice atom is demonstrated to be feasible for realizing precise regulation of the electronic structures and thus catalytic activity of the nanosheets. [ABSTRACT FROM AUTHOR]

For electrocatalysts for the hydrogen evolution reaction (HER), encapsulating transition metal phosphides (TMPs) into nitrogen‐doped carbon materials has been known as an effective strategy to elevate the activity and stability. Yet still, it remains unclear how the TMPs work synergistically with the N‐doped support, and which N configuration (pyridinic N, pyrrolic N, or graphitic N) contributes predominantly to the synergy. Here we present a HER electrocatalyst (denoted as MoP@NCHSs) comprising MoP nanoparticles encapsulated in N‐doped carbon hollow spheres, which displays excellent activity and stability for HER in alkaline media. Results of experimental investigations and theoretical calculations indicate that the synergy between MoP and the pyridinic N can most effectively promote the HER in alkaline media. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bifunctional Mo1@CNNTs photocatalyst was prepared through a facile strategy. • Mo1@CNNTs achieved 97.3% TC degradation and 4861µmolh−1 g−1 H 2 evolution rate. • Unveiled critical role of atomic Mo sites in activating O 2 into reactive species. • O 2 activation and H 2 evolution mechanisms were revealed by DFT calculations. Metal single atom catalysts (MSACs) stabilized by nitrogen in carbon nitride are intriguing photocatalysts for energy and environmental applications. However, the synergistic effect of simultaneously tailoring the carbon nitride nanostructure and fabricating single metal atoms has not been explored for photocatalysis. Herein, we report the facile synthesis of Mo atomic sites on porous carbon nitride nanotubes (Mo1@CNNTs) obtained by template free polymerization of urea and melamine monomers. AC-HAADF-STEM image confirmed the existence of isolated Mo atoms, while XAS analysis revealed the formation of unique atomic Mo-N 3 structures on CNNTs. Incorporation of Mo atomic sites into CNNTs modulated electronic and band structure and thus improved light harvesting, charge separation, and transfer. The synergy of 1D nanotube structure and distinct atomic Mo sites turned Mo1@CNNTs as a highly efficient bifunctional photocatalyst for hydrogen evolution and tetracycline degradation. On one side Mo1@CNNTs demonstrated hydrogen evolution rate of 4861 µmol.h−1.g−1, while on the other hand Mo1@CNNTs achieved 97.3% TC degradation under visible light irradiation. DFT investigations revealed that induction of unique Mo atomic sites not only tuned the electronic structure of CNNTs, but also localized photoexcited electrons around Mo atoms to activate O 2 (ads) and generate reactive species (.O 2 –/.OH) for TC degradation. We believe that our findings are promising and will open new opportunities for the design of novel photocatalyst for a sustainable future. [ABSTRACT FROM AUTHOR]

[Display omitted] • A supramolecular-confinement pyrolysis strategy is proposed to fabricate ultra-dispersed Ni-Mo 2 C nanoparticles. • POMs-based supramolecular aggregate act as pre-assembling molecular platform for regulating Mo 2 C structure at atomic level. • Atomically dispersed Ni doping and Ni-P catalyst-substrate coupling synergistically enhance the intrinsic activity of Mo 2 C. • Ni-Mo 2 C/NPC exhibits excellent electrocatalytic activity and durability for HER in acidic and alkaline conditions. • The EXAFS and DFT calculations confirm that Mo(C)–Ni–P configuration is the origin of outstanding HER activities. Herein, a novel supramolecular-confinement pyrolysis strategy was proposed to construct ultrafine Ni-Mo 2 C nanoparticles uniformly distributed on N,P co-doped carbon (NPC) by using polyoxometalate supramolecular aggregate as precursor. Ni-Mo 2 C/NPC exhibits remarkable electrocatalytic activity for hydrogen evolution reaction (HER) in both acidic and alkaline conditions, as well as superior long-term durability. Combining EXAFS with DFT calculations, we demonstrate that Ni species were atomically dispersed and anchored by Mo 2 C lattice and P atoms from NPC, thus defining Mo(C)–Ni–P active sites, which enhance the intrinsic catalytic activity of Mo 2 C by atomic-scale Ni doping and Ni–P catalyst-substrate chemical coupling. The Mo(C)–Ni–P sites have optimal hydrogen adsorption free energies and can precisely regulate and activate the neighboring C, leading to excellent HER performance. This work developed a "bottom-up" polyoxometalate-based supramolecular approach for in-situ assembly of high-active HER catalytic sites, which will provide opportunities to design and fabricate low-cost and efficient atomic-scale catalysts for clean energy conversion. [ABSTRACT FROM AUTHOR]

The single-atom ruthenium doped monolayered TiO 2 nanosheets are successfully synthesized. The single-atom Ru 1 introduces an impurity energy level, allowing light absorption up to 700 nm, and an oxygen vacancy around Ru 1 tends to be a charge trapping site, promoting rapid photogenerated electron separation and transportation, facilitating photocatalytic hydrogen evolution reaction under visible light irradiation. • The single-atom ruthenium doped monolayered TiO 2 nanosheets (Ru 1 /TiNS) were successfully prepared. • The Ru 1 /TiNS introduced an impurity energy level which extended light absorption up to 700 nm. • The Ru 1 /TiNS generated oxygen vacancies which promoted photogenerated electron separation and transportation. • The DFT calculation revealed Ru 1 atom was both thermodynamically and kinetically favorable for photocatalytic H 2 production. • Ru 1 /TiNS enabled efficient H 2 evolution of 4.81 mmol h-1 g-1 under visible light, comparable to 8.95 mmol h-1 g-1 under full light spectrum. Efficient visible-light-driven hydrogen evolution (VLD-HER) is the most desirable for utilizing solar energy, but it remains a significant challenge to fabricate advanced photocatalysts. Herein, we report on a single-atom ruthenium doped monolayered TiO 2 nanosheet catalyst (Ru 1 /TiNS). Unlike pure TiO 2 with no VLD-HER activity, Ru 1 /TiNS enables efficient H 2 evolution with a mmol h−1 g−1 magnitude (4.81) under visible light, comparable to 8.95 mmol h−1 g−1 under full light spectrum. Various ex-/in -situ characterizations and theoretical calculations reveal that the single-atom Ru 1 introduces an impurity energy level, allowing light absorption up to 700 nm, and an oxygen vacancy around Ru 1 tends to be a charge trapping site, promoting rapid photogenerated electron separation and transportation. This study provides a promising catalyst-design strategy for high-efficiency hydrogen production using solar energy. [ABSTRACT FROM AUTHOR]