Polymeric carbon nitride (CN) as a metal-free photocatalyst holds great promise to produce high-value chemicals and H₂ fuel utilizing clean solar energy. However, the wider deployment of pristine CN is critically hampered by the poor charge carrier transport and high recombination. Herein, we develop a facile salt template-assisted interfacial polymerization strategy that in-situ introduces alkali ions (Na⁺, K⁺) and nitrogen defects in CN (denoted as v-CN-KNa) to simultaneously promote charge separation and transportation and steer photoexcited holes and electrons to their oxidation and reduction sites. The photocatalyst exhibits an impressive photocatalytic H₂ evolution rate of 8641.5 μmol·g⁻¹·h⁻¹ (33-fold higher than pristine CN) and also works readily in real seawater (10752.0 μmol·g⁻¹·h⁻¹) with a high apparent quantum efficiency up to 18.5% at 420 nm. In addition, we further demonstrate that the v-CN-KNa can simultaneously produce H₂ and N-benzylidenebenzylamine without using any other sacrificial reagent. In situ characterizations and DFT calculations reveal that the alkali ions notably promote charge transport, while the nitrogen defects generate abundant edge active sites, which further contribute to efficient electron excitation to trigger photoredox reactions.

Taking advantage of the unique layered structure of TiSe₂, the intrinsic electronic properties of two-dimensional materials can easily be tuned via heteroatomic engineering. Herein, we show that the charge density wave (CDW) phase in 1T-TiSe₂ single-crystals can be gradually suppressed through Sn atoms intercalation. Using angle-resolved photoemission spectroscopy (ARPES) and temperature-dependent resistivity measurements, this work reveals that Sn atoms can induce charge doping and modulate the intrinsic electronic properties in the host 1T-TiSe_2. Notably, our temperature-dependent ARPES results highlight the role exciton-phonon interaction and the Jahn-Teller mechanism through the formation of backfolded bands and exhibition of a downward Se shift of 4p valence band in the formation of CDW in this material.

Nontrivial topological behaviors in superconducting materials provide resourceful ground for the emergence and study of unconventional quantum states. Charge doping by the controlled intercalation of donor atoms is an efficient route for enhancing/inducement of superconducting and topological behaviors in layered topological insulators and semimetals. Herein, we enhanced the superconducting temperature of TaSe₂ by 20-folds (~ 3 k) through Sn atoms intercalation. Using first-principles calculations, we demonstrated the existence of nontrivial topological features. Sn_0.5TaSe₂ displays topological nodal lines around the K high symmetry point in the Brillouin zone, with drumhead-like shaped surface states protected by inversion symmetry. Altogether, the coexistence of these properties makes Sn_0.5TaSe₂ a potential candidate for topological superconductivity.

To fully realize the commercial viability of Pt in fuel cells, the usage of scarce Pt must be reduced while the activity and durability in O₂ reduction reaction (ORR) must be enhanced. Here we report a metallic stack design achieving these goals for ORR, based on atomically precise materials synthesis. Au@Pd@Pt nanostructures with atomically thin Pt shells and high-index surfaces form an excellent platform for integrating the effects of electronic structures, surface facets, and substrate stabilization to boost ORR performance. Au@Pd@Pt trisoctahedrons (TOH) achieve mass activity 6.1 times higher than that of commercial Pt/C and dramatically enhanced durability beyond 1.0 V vs. a reversible hydrogen electrode in oxidation potential. Meanwhile, Pt comprises only 3.2% of the nanostructures. To further improve the ORR activity and demonstrate the versatility of our strategy, we implement the same design in PtNi alloy electrocatalysts. The Au@Pd@PtNi TOHs exhibit mass activity 14.3 times higher than that of commercial Pt/C as well as excellent durability. This work demonstrates an alternative strategy for fabricating high-performance and low-cost catalysts, and highlights the importance of simultaneous surface and interfacial engineering with atomic precision in designing catalysts.

In most cases, layered transition metal dichalcogenides (LTMDs), containing metallic phases, show electrochemical behavior different from their semiconductor counterparts. Typically, two-dimensional layered metallic 1T-MoS₂ demonstrates better electrocatalytic performance for water splitting compared to its 2H counterpart. However, the characteristics of low metallic phase concentration and poor stability limit its applications in some cases. Herein, we demonstrate a simple and efficient bottom-up wet-chemistry strategy for the large-scale synthesis of nanoscopic ultrathin Mo_1-xW_xS₂ nanosheets with enlarged interlayer spacing and high metallic phase concentration. Our characterizations, including X-ray absorption fine structure spectroscopy (XAFS), high-angle annular dark-fieldscanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS) revealed that the metallic ultrathin ternary Mo_1-xW_xS₂ nanosheets exhibited distorted metal-metal bonds and a tunable metallic phase concentration. As a proof of concept, this optimized catalyst, with the highest metallic phase concentration (greater than 90%), achieved a low overpotential of about-155 mV at a current density of -10 mA/cm², a small Tafel slope of 67 mV/dec, and an increased turnover frequency (TOF) of 1.3 H₂ per second at an overpotential of -300 mV (vs. reversible hydrogen electrode (RHE)), highlighting the importance of the metallic phase. More importantly, this study can lead to a facile solvothermal route to prepare stable and high-metallicphase-concentration transition-metal-based two-dimensional materials for future applications.