Photocatalytic hydrogen evolution coupled with organic oxidation holds great promise for converting solar energy into high-value-added chemicals, but it is hampered by sluggish charge dynamics and limited redox potential. Herein, a porous S-doped carbon nitride (S-C₃N_4-y) foam assembled from ultrathin nanosheets with rich nitrogen vacancies was synthesized using a molecular self-assembly strategy. The S dopants and N vacancies synergistically adjusted the band structure, facilitating light absorption and enhancing the oxidation ability. Moreover, the ultrathin nanosheets and porous structure provided more exposed active sites and facilitated mass and charge transfer. Consequently, S-C₃N_4-y foam exhibited enhanced photocatalytic activities for synchronous hydrogen evolution (4960 μmol/h/g) and benzylamine oxidation to N-benzylidenebenzylamine (4885 μmol/h/g) with high selectivity of > 99 %, which were approximately 17.6 and 72.9 times higher than those of bulk CN, respectively. The photocatalytic coupling pairing reaction promote the water splitting by consuming H₂O₂, thereby improving the hydrogen evolution efficiency and achieving the production of high value-added imines. This study provides an effective route for regulating the morphology and band structure of carbon nitride for synthesizing highly valuable chemicals.

FeNi-based phosphides are one of the most hopeful electrocatalysts, whereas the significant challenge is to achieve prominent bifunctional catalytic activity with low voltage for water splitting. The morphology and electronic structure of FeNi-based phosphides can intensively dominate effective catalysis, therefore their simultaneous regulating is extremely meaningful. Herein, a robust bifunctional catalyst of Zn-implanted FeNi-P nanosheet arrays (Zn-FeNi-P) vertically well-aligned on Ni foam is successfully fabricated by Zn implanting strategy. The Zn fulfills the role of electronic donor due to its low electronegativity to enhance the electronic density of FeNi-P for optimized water dissociation kinetics. Meanwhile, the implantation of Zn into FeNi-P can effectively regulate morphology of the catalyst from thick and irregular nanosheets to ultrathin lamellar structure, which generates enriched catalytic active sites, leading to accelerating electron/mass transport ability. Accordingly, the designed Zn-FeNi-P catalyst manifests remarkable hydrogen evolution reaction (HER) activity with low overpotentials of 55 and 225 mV at 10 and 200 mA·cm⁻², which is superior to the FeNi-P (82 mV@10 mA·cm⁻² and 301 mV@200 mA·cm⁻²), and even out-performing the Pt/C catalyst at a high current density > 200 mA·cm⁻². Moreover, the oxygen evolution reaction (OER) activity of Zn-FeNi-P also has dramatically improved (207 mV@10 mA·cm⁻²) comparable to FeNi-P (221 mV@10 mA·cm⁻²) and RuO₂ (239 mV@10 mA·cm⁻²). Noticeably, an electrolyzer based on Zn-FeNi-P electrodes requires a low cell voltage of 1.47 V to achieve 10 mA·cm⁻², far beyond the catalytic activities of FeNi-P||FeNi-P (1.51 V@10 mA·cm⁻²) and the benchmark RuO₂||Pt/C couples (1.56 V@10 mA·cm⁻²). This Zn-implanting strategy paves a new perspective for the development of admirable bifunctional catalysts.

The formation of chemical bonds between metal ions and their supports is an effective strategy to achieve good catalytic activity. However, both the synthesis of active metal species on a support and control of their coordination environment are still challenging. Here, we show the use of an organic compound to produce tubular carbon nitride (TCN) as a support for Pd nanoparticles (NPs), creating a composite material (NP-Pd-TCN). It was found that Pd ions preferentially bind with the electron-rich N atoms of TCN, leading to strong metal–support interactions that benefit charge transfer from g-C₃N₄ to Pd. X-ray absorption spectroscopy further revealed that the metal–support interactions resulted in the formation of Pd–N bonds, which are responsible for the improvement in the charge dynamics as evidenced by the results from various techniques including photoluminescence (PL) spectroscopy, photocurrent measurements, and electrochemical impedance spectroscopy (EIS). Owing to the good dynamical properties, NP-Pd-TCN was used for photocatalytic hydrogen evolution under visible-light irradiation (λ > 420 nm) and an excellent evolution rate of ~ 381 μmol·h ⁻¹ (0.02 g of the photocatalyst) was attained. This work aims to promote a strategy to synthesize efficient photocatalysts for hydrogen production by controllably introducing metal nanoparticles on a support and in the meantime forming chemical bonds to achieve intimate metal-support contact.

Developing cost-efficient electrocatalysts for oxygen evolution is vital for the viability of H₂ energy generated via electrolytic water. Engineering favorable defects on the electrocatalysts to provide accessible active sites can boost the sluggish reaction thermodynamics or kinetics. Herein, Co_1-xS nanosheets were designed and grown on reduced graphene oxide (rGO) by controlling the successive two-step hydrothermal reaction. A belt-like cobalt-based precursor was first formed with the assistance of ammonia and rGO, which were then sulfurized into Co_1-xS by L-cysteine at a higher hydrothermal temperature. Because of the non-stoichiometric defects and ultrathin sheet-like structure, additional cobalt vacancies (V'_Co) were formed/exposed on the catalyst surface, which expedited the charge diffusion and increased the electroactive surface in contact with the electrolyte. The resulting Co_1-xS/rGO hybrids exhibited an overpotential as low as 310 mV at 10 mA·cm^-2 in an alkaline electrolyte for the oxygen evolution reaction (OER). Density functional theory calculations indicated that the V'_Co on the Co_1-xS/rGO hybrid functioned as catalytic sites for enhanced OER. They also reduced the energy barrier for the transformation of intermediate oxygenated species, promoting the OER thermodynamics.

Murdochite-type Ni₆MnO₈ three-dimensional mesoporous nanosheet arrays grown on carbon cloth (NMO-SA/CC) are synthesized using an in-situ growth strategy. As self-supported binder-free anodes for LIBs, the NMO-SA/CC hierarchical nanostructures exhibit ultrahigh capacity, excellent cycling stability, and good rate capability. The excellent lithium storage performance can be ascribed to the perfect electrical contact between NMO-SA and CC. The mesopores in the thin nanosheet can maximize the electrode contact with the electrolyte by decreasing the Li⁺ diffusion path. Moreover, these effects relieve the pulverization and agglomeration that originate from the large volume variations during the Li⁺ intercalation/deintercalation cycles. The in-situ X-ray absorption fine structure (XAFS) spectrum recorded during the initial lithiation/delithiation processes reveals the conversion reaction process.

The catalytic activity of materials is highly dependent on their composition and surface structure, especially the density of low-coordinated surface atoms. In this work, we have prepared two-dimensional hexagonal FeS with high-energy (001) facets (FeS-HE-001) via a solution-phase chemical method. Nanosheets (NSs) with exposed high-energy planes usually possess better reaction activity, so FeS-HE-001 was used as a counter electrode (CE) material for dye-sensitized solar cells (DSSCs). FeS-HE-001 achieved an average power conversion efficiency (PCE) of 8.88% (with the PCE of champion cells being 9.10%), which was almost 1.15 times higher than that of the Pt-based DSSCs (7.73%) measured in parallel. Cyclic voltammetry and Tafel polarization measurements revealed the excellent electrocatalytic activities of FeS-HE-001 towards the I ₃^–/I^– redox reaction. This can be attributed to the promotion of photoelectron transfer, which was measured by electrochemical impedance spectroscopy and scanning Kelvin probe, and the strong I ₃^– adsorption and reduction activities, which were investigated using first-principles calculations. The presence of high-energy (001) facets in the NSs was an important factor for improving the catalytic reduction of I ₃^–. We believe that our method is a promising way for the design and synthesis of advanced CE materials for energy harvesting.

Highly sensitive, selective, and stable hydrogen peroxide (H₂O₂) detection using nanozyme-based catalysts are desirable for practical applications. Herein, vertical α-FeOOH nanowires were successfully grown on the surface of carbon fiber paper (CFP) via a low-temperature hydrothermal procedure. The formation of vertical α-FeOOH nanowires is ascribed to the structure-directing role of sodium dodecyl sulfate. The resulting free-standing electrode with one-dimensional (1D) nanowires offers oriented channels for fast charge transfer, excellent electrical contact between the electrocatalyst and the current collector, and good mechanical stability and reproducibility. Thus, it can serve as an efficient electrocatalyst for the reduction and sensitive detection of H₂O₂. The relation of the oxidation current of H₂O₂ with the concentration is linear from 0.05 to 0.5 mM with a sensitivity of -0.194 mA/(mM·cm²) and a low detection limit of 18 μM. Furthermore, the portability in the geometric tailor and easy device fabrication allow extending the general applicability of this free-standing electrode to chemical and biological sensors.

A cost-efficient and stable oxygen evolution electrocatalyst is essential for improving energy storage and conversion efficiencies. Herein, 2D nanosheets with randomly cross-linked CoNi layered double hydroxide (LDH) and small CoO nanocrystals were designed and synthesized via in situ reduction and interfacedirected assembly in air. The formation of CoNi LDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal–oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O 2p orbitals, and electron transfer between metal atoms through Ni–O–Co, a number of Co and Ni atoms in the CoNi LDH present a high +3 valency. These unique characteristics result in a high density of oxygen evolution reaction (OER) active sites, improving the affinity between OH^– and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER. The CoNi LDH/CoO featured a low onset potential of 1.48 V in alkaline medium, and required an overpotential of only 300 mV at a current density of 10 mA·cm^–2, while displaying good stability in accelerated durability tests.

The application of direct methanol fuel cells (DMFC) is hampered by high cost, low activity, and poor CO tolerance by the Pt catalyst. Herein, we designed a fancy 3D hybrid by anchoring tungsten nitride (WN) nanoparticles (NPs), of about 3 nm in size, into a 3D carbon nanotube-reduced graphene oxide framework (CNT-rGO) using an assembly route. After depositing Pt, the contacted and strongly coupled Pt–WN NPs were formed, resulting in electron transfer from Pt to WN. The 3D Pt–WN/CNT-rGO hybrid can be used as a bifunctional electrocatalyst for both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). In MOR, the catalysts showed excellent CO tolerance and a high mass activity of 702.4 mA·mg_Pt^–1, 2.44 and 3.81 times higher than those of Pt/CNT-rGO and Pt/C(JM) catalysts, respectively. The catalyst also exhibited a more positive onset potential (1.03 V), higher mass activity (151.3 mA·mg_Pt^–1), and better cyclic stability and tolerance in MOR than ORR. The catalyst mainly exhibited a 4e-transfer mechanism with a low peroxide yield. The high activity was closely related to hybrid structure. That is, the 3D framework provided a favorable path for mass-transfer, the CNT-rGO support was favorable for charge transfer, and strongly coupled Pt–WN can enhance the catalytic activity and CO-tolerance of Pt. Pt–WN/CNT-rGO represents a new 3D catalytic platform that is promising as an electrocatalyst for DMFC because it can catalyze both ORR and MOR in an acidic medium with good stability and highly efficient Pt utilization.

Graphene nanosheets possess a promising potential as electrodes in Li-ion batteries (LIBs); consequently, the development of low-cost and high-productivity synthetic approaches is crucial. Herein, porous graphene-like nanosheets (PGSs) have been synthesized from expandable graphite (EG) by initially intercalating phosphoric acid, and then performing annealing to enlarge the interlayer distance of EG, thus facilitating the successive intercalation of zinc chloride. Subsequently, the following pyrolysis of zinc chloride in the EG interlayer promoted the formation of the porous PGS structure; meanwhile, the gas produced during the formation of the porous structure could exfoliate the EG to graphene-like nanosheets. The synthetic PGS material used as LIB anode exhibited superior Li⁺ storage performance, showing a remarkable discharge capacity of 830.4 mAh·g^-1 at 100 mA·g^-1, excellent rate capacity of 211.6 mAh·g^-1 at 20, 000 mA·g^-1, and excellent cycle performance (near 100% capacity retention after 10, 000 cycles). The excellent rate performance is attributed to the Li⁺ ion rapid transport in porous structures and the high electrical conductivity of graphene-like nanosheets. It is expected that PGS may be widely used as anode material for high-rate LIBs via this facile and low-cost route by employing EG as the raw material.