Exploring noble-metal-free electrocatalysts with high efficiency for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) holds promise for advancing the production of H2 fuel through water splitting. Herein, one-pot synthesis was introduced for MoS2–Ni3S2 heteronanorods supported by Ni foam (MoS2–Ni3S2 HNRs/NF), in which the Ni3S2 nanorods were hierarchically integrated with MoS2 nanosheets. The hierarchical MoS2–Ni3S2 heteronanorods allow not only the good exposure of highly active heterointerfaces but also the facilitated charge transport along Ni3S2 nanorods anchored on conducting nickel foam, accomplishing the promoted kinetics and activity for HER, OER, and overall water splitting. The optimal MoS2–Ni3S2 HNRs/NF presents low overpotentials (η10) of 98 and 249 mV to reach a current density of 10 mA cm–2 in 1.0 M KOH for HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, such heteronanorods show a quite low cell voltage of 1.50 V at 10 mA cm–2 and remarkable stability for more than 48 h, which are among the best values of current noble-metal-free electrocatalysts. This work elucidates a rational design of heterostructures as efficient electrocatalysts, shedding some light on the development of functional materials in energy chemistry.Keywords: electrocatalysis; heterointerfaces; hydrogen evolution reaction; metal sulfides; overall water splitting; oxygen evolution reaction;

Surface engineering is crucial to improve the biocompatibility and sensing response of two-dimensional (2D) nanomaterials. For nanostructured MoS2 biosensors, post functionalization via cumbersome procedures unfortunately leads to inevitable structural damage and thus reduced functionalities. Herein, in situ surface functionalization by the reactant thiourea (TU) was employed to one-step fabricate TU-capped MoS2 (TU-MoS2) nanosheets. The amino-group terminated surface of TU-MoS2 favours immobilization of the GE11 peptide that can specifically recognize cancer cells. The resulting sensor shows high sensitivity and selectivity in detecting cancer cells, relying on the varied expression of the epidermal growth factor receptor (EGFR) on cell membranes. In the case of human liver cancer cells, it is featured by a wide linear range (50–106 cells mL−1) and a low detection limit (50 cells mL−1) in electrochemical impedance spectroscopy, as the variation of charge-transfer resistance is plotted against cell concentration. Furthermore, it exhibits good efficiency in monitoring the dynamic variation of EGFR expression on living cells in response to drug treatment, which is promising for clinical diagnosis and drug screening in miniaturization. By elucidating an efficient biosensing platform on the basis of surface engineered MoS2 nanosheets, this work sheds some light on the development of biosensing technology and relevant materials.

To explore high-performance electrocatalysts, electronic regulation on active sites is essentially demanded. Herein, we propose controlled phosphorus doping to effectively modify the electronic configuration of nanostructured Mo2C, accomplishing a benchmark performance of noble-metal-free electrocatalysts in the hydrogen evolution reaction (HER). Employing MoOx–phytic acid–polyaniline hybrids with tunable composition as precursors, a series of hierarchical nanowires composed of phosphorus-doped Mo2C nanoparticles evenly integrated within conducting carbon (denoted as P-Mo2C@C) are successfully obtained via facile pyrolysis under inert flow. Remarkably, P-doping into Mo2C can increase the electron density around the Fermi level of Mo2C, leading to weakened Mo–H bonding toward promoted HER kinetics. Further density functional theory calculations show that the negative hydrogen-binding free energy (ΔGH*) on pristine Mo2C gradually increases with P-doping due to electron transfer and steric hindrance by P on the Mo2C surface, indicating the effectively weakened strength of Mo–H. With optimal doping, a ΔGH* approaching 0 eV suggests a good balance between the Volmer and Heyrovsky/Tafel steps in HER kinetics. As expected, the P-Mo2C@C nanowires with controlled P-doping (P: 2.9 wt%) deliver a low overpotential of 89 mV at a current density of −10 mA cm−2 and striking kinetic metrics (onset overpotential: 35 mV, Tafel slope: 42 mV dec−1) in acidic electrolytes, outperforming most of the current noble-metal-free electrocatalysts. Elucidating feasible electronic regulation and the remarkably enhanced catalysis associated with controlled P-doping, our work will pave the way for developing efficient noble-metal-free catalysts via rational surface engineering.

Exploring efficient noble-metal free electrocatalysts for the hydrogen evolution reaction (HER) is one of the most promising pathways for facing the energy crisis. Herein, MoC–Mo2C heteronanowires composed of well-defined nanoparticles were accomplished via controlled carbonization, showing excellent HER activity, fast kinetic metrics and outstanding stability in both acid and basic electrolytes. In particular, the optimal one consisting of 31.4 wt% MoC displayed a low overpotential (η10 = 126 and 120 mV for reaching a current density of −10 mA cm−2), a small Tafel slope (43 and 42 mV dec−1) and a low onset overpotential (38 and 33 mV) in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such prominent performance, outperforming most of the current noble-metal free electrocatalysts, was ascribed to the carbide surface with an optimized electron density, and the consequently facilitated HER kinetics. This work elucidates a feasible way toward efficient electrocatalysts via heteronanostructure engineering, shedding some light on the exploration and optimization of catalysts in energy chemistry.

Transition metal carbides are an emerging class of anode materials for Li-ion batteries (LIBs), which have recently drawn attention because of their good conductivity and high capacity after rational nano-engineering. In this work, we have developed Mo2C/N-doped carbon mesoporous heteronanowires (Mo2C/N–C MHNWs) with enhanced capacitive behaviour as high-performance anode materials for LIBs. With the heterostructure, the Mo2C nanocrystallites offer short paths for Li+ diffusion, while the N-doped carbon matrix facilitates fast electron transportation and buffers the volume change of Mo2C during the discharge/charge cycles. When evaluated as anodes for LIBs, the Mo2C/N–C MHNWs exhibited high capacity and high rate capability, as well as a long-term cycle life. In particular, a reversible capacity of 744.6 mA h g−1 was achieved in the first cycle, and 732.9 mA h g−1 was preserved after 700 cycles at a current density of 2 A g−1. The outstanding performance stems from fast kinetics enhanced by the pseudocapacitive effect, which was evidenced in the further analysis based on electrochemical impedance spectra and cyclic voltammetry. Our results elucidate the attractive Li+ storage performance of Mo2C-based nanocomposites, which may shed some light on the development of high-performance materials for energy storage and utilization.

The hydrogen evolution reaction using noble-metal free electrocatalysts has captured increasing attention due to its importance in renewable hydrogen production. Herein, a highly active and stable electrocatalyst of MoC encapsulated by graphitized carbon shells (nanoMoC@GS) has been developed via an in situ carburization of a Mo-based metal–organic framework (Mo-MOF) with the atomic periodic structure. The ultrafine MoC nanoparticles (∼3 nm) confined by 1–3 layered graphite shells significantly favor the efficient HER in both acidic and basic media. In particular, a low overpotential (η10 = 124 and 77 mV at a current density of −10 mA cm−2), a small Tafel slope (43 and 50 mV dec−1) and a high exchange current density (j0 = 0.015 and 0.212 mA cm−2) are achieved on nanoMoC@GS in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such remarkable activity, outperforming most current noble-metal-free electrocatalysts, stems from the cooperative/synergistic effects of ultrafine MoC nanostructure, ultrathin and conductive graphitized carbon shells, and enriched porosity. This work demonstrates a feasible way to design high-performance electrocatalysts via converting “atomic contact” hybrid structures (e.g., MOFs), illustrating a new perspective for developing nanocatalysts in the energy chemistry field.

•MoO2 nanoparticles are anchored on and embedded in the 1-D N-doped carbon matrix.•The heterostructure exhibits good rate capability and long-term cycle life.•Pseudocapacitive effect promotes the Li+ storage kinetics of MoO2/N-C H-NWs.Hierarchical MoO2/N-doped carbon heteronanowires (MoO2/N-C H-NWs) are synthesised by simple calcination using organic–inorganic hybrid nanowires as a precursor and self-template. In the heterostructure, MoO2 nanoparticles are not only anchored on but also embedded in the one-dimensional N-doped carbon matrix. The synergistic effect promotes the pseudocapacitance, decreases the charge transfer resistance, and buffers the volume change on the reaction of MoO2/N-C H-NWs with Li+. Therefore it endows the composite with enhanced kinetics and stability for reversible Li+ storage. At a current density of 2 A g−1, the MoO2/N-C H-NWs deliver a reversible capacity of 700 mAh g−1 after 400 cycles, which still remains 570 mAh g−1 even after 1500 cycles. The high capability suggests that the MoO2/N-C H-NWs may be a promising candidate for use as anode material in high-performance lithium-ion batteries.

•The biomass-derived sources are used to fabricate well-defined MoCx/CN.•Superior electrochemical HER performances are presented on MoCx/CN nanocomposites.•N-doping controlled by synthesis is important for achieving efficient MoCx/CN.Exploring noble-metal free electrocatalysts remains a great challenge for hydrogen evolution reaction (HER). Herein, we report the fabrication of molybdenum carbides supported by N-doped carbon (MoCx/CN), employing glucose and melamine as precursors to generate conducting supports. The nanosized MoCx, and its intimate contact with CN, favor the efficient HER. The optimal MoCx/CN delivers an overpotential (η) of 220 mV to produce a current density (j) of 10 mA cm−2, and a high j of 72 mA cm−2 at η=300 mV in 0.5 M H2SO4.

•Efficient Ir/H-MoOx catalysts were fabricated via one-pot strategy.•Strong electronic metal-support interactions were evidenced in Ir/H-MoOx.•Ir/H-MoOx shows highly chemoselective hydrogenation for various α,β-unsaturated aldehydes.As reducible supports, metal oxides present the varied charge effect after hydrogen doping and partial reduction, accomplishing the tunable metal-support interactions and the promoted catalytic turnover in heterogeneous catalysis. Herein, the one-pot fabrication of hydrogenated MoOx (H-MoOx) nanorods supported Ir (Ir/H-MoOx) was developed, which simultaneously combined the generation of active centers (Ir) and the hydrogen doping on supports (H-MoOx). Because of the accumulated electrons around MoO6 octahedras after hydrogen doping, the electronic perturbations arising from H-MoOx supports led to the negatively charge Irδ− species being beneficial for the selective hydrogenation of CO moiety in α,β-unsaturated aldehydes. In the hydrogenation of cinnamaldehyde to cinnamyl alcohol, Ir/H-MoOx delivered selectivity as high as ∼93%, performing among the best of current metal-based catalysts. Additionally, the efficacy for various substrates with multiple groups further verified our Ir/H-MoOx system to be competitive for chemoselective hydrogenation.H2 spillover on in-situ formed Ir was utilized to hydrogenate MoO3 on-site, accomplishing the hydrogenated MoOx supported Ir for the chemoselective hydrogenation of α,β-unsaturated aldehydes. The active Irδ- species resulting from the strong electronic metal-support interactions is responsible for the selective CO hydrogenation.

The exposure of rich active sites is crucial for MoS2 nanocatalysts in efficient hydrogen evolution reaction (HER). However, the active (010) and (100) planes tend to vanish during preparation because of their high surface energy. Employing the protection by thiourea (TU) reactant, a microwave-assisted reactant-protecting strategy is successfully introduced to fabricate active-site-rich MoS2 (AS-rich MoS2). The bifunctionality of TU, as both a reactant and a capping agent, ensures rich interactions for the effective protection and easy exposure of active sites in MoS2, avoiding the complicated control and fussy procedure related to additional surfactants and templates. The as-obtained AS-rich MoS2 presents the superior HER activity characterized by its high current density (j = 68 mA cm–2 at −300 mV vs RHE), low Tafel slope (53.5 mV dec–1) and low onset overpotential (180 mV), which stems from the rich catalytic sites and the promoted conductivity. This work elucidates a feasible way toward high performance catalysts via interface engineering, shedding some light on the development of emerging nanocatalysts.Keywords: active sites; hydrogen evolution; microwave; molybdenum disulfide; reactant-protecting

The electron regulation on supports can vary metal-support interactions with loaded metals in heterogeneous catalysis. In this paper, a facile Sr2+-mediated ionothermal route was introduced to control the nitridation degree in tantalum (oxy)nitrides, resulting in varied electronic properties and optimized interactions with gold nanocatalysts. A new mechanism was proposed that the formation of SrTa4O11 intermediates facilitated the replacement of O by N in controlled nitridation, and more importantly avoided undesired over-nitridation. As expected, the TaON support with defined nitridation promoted electronic metal-support interactions to generate Auδ− species, which was highly active for the thermal hydrogenation of nitrobenzene due to the moderated adsorption and effective activation on Auδ− in Au/TaON. This work elucidated the optimized metal-support interactions achieved on controllably nitridated supports, opening up new opportunities for the development of efficient nanocatalysts.

•Firstly applying Mo2C/N-C HNWs in sodium ion batteries (SIBs).•The hybrid nanostructure enables good performance of Na+ storage.•Such material will be a new promising anode material for SIBs.Herein we report Mo2C/N-doped carbon hierarchical nanowires (Mo2C/N-C HNWs) as anode materials for sodium-ion batteries. In the Mo2C/N-C HNWs, Mo2C nanocrystallites are uniformly distributed in N-doped carbon matrix. The nanocrystallites of Mo2C offer short paths for Na+ diffusion, the mesoporous structure facilitates the diffusion of electrolyte, and the N-doped carbon matrix accelerates the electron transfer. As anode materials for sodium-ion batteries, the Mo2C/N-C HNWs exhibited reversible capacities of 381 and 308 mAh g−1 at current densities of 50 and 200 mA g−1, respectively. Our results demonstrate the enhanced Na+ storage activity of Mo2C after structure tailoring, elucidating the potential of transition-metal carbides as promising anode materials for sodium-ion batteries.

The hydrogen evolution reaction using noble-metal free electrocatalysts has captured increasing attention due to its importance in renewable hydrogen production. Herein, a highly active and stable electrocatalyst of MoC encapsulated by graphitized carbon shells (nanoMoC@GS) has been developed via an in situ carburization of a Mo-based metal–organic framework (Mo-MOF) with the atomic periodic structure. The ultrafine MoC nanoparticles (∼3 nm) confined by 1–3 layered graphite shells significantly favor the efficient HER in both acidic and basic media. In particular, a low overpotential (η10 = 124 and 77 mV at a current density of −10 mA cm−2), a small Tafel slope (43 and 50 mV dec−1) and a high exchange current density (j0 = 0.015 and 0.212 mA cm−2) are achieved on nanoMoC@GS in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such remarkable activity, outperforming most current noble-metal-free electrocatalysts, stems from the cooperative/synergistic effects of ultrafine MoC nanostructure, ultrathin and conductive graphitized carbon shells, and enriched porosity. This work demonstrates a feasible way to design high-performance electrocatalysts via converting “atomic contact” hybrid structures (e.g., MOFs), illustrating a new perspective for developing nanocatalysts in the energy chemistry field.

Surface engineering is crucial to improve the biocompatibility and sensing response of two-dimensional (2D) nanomaterials. For nanostructured MoS2 biosensors, post functionalization via cumbersome procedures unfortunately leads to inevitable structural damage and thus reduced functionalities. Herein, in situ surface functionalization by the reactant thiourea (TU) was employed to one-step fabricate TU-capped MoS2 (TU-MoS2) nanosheets. The amino-group terminated surface of TU-MoS2 favours immobilization of the GE11 peptide that can specifically recognize cancer cells. The resulting sensor shows high sensitivity and selectivity in detecting cancer cells, relying on the varied expression of the epidermal growth factor receptor (EGFR) on cell membranes. In the case of human liver cancer cells, it is featured by a wide linear range (50–106 cells mL−1) and a low detection limit (50 cells mL−1) in electrochemical impedance spectroscopy, as the variation of charge-transfer resistance is plotted against cell concentration. Furthermore, it exhibits good efficiency in monitoring the dynamic variation of EGFR expression on living cells in response to drug treatment, which is promising for clinical diagnosis and drug screening in miniaturization. By elucidating an efficient biosensing platform on the basis of surface engineered MoS2 nanosheets, this work sheds some light on the development of biosensing technology and relevant materials.

Transition metal carbides are an emerging class of anode materials for Li-ion batteries (LIBs), which have recently drawn attention because of their good conductivity and high capacity after rational nano-engineering. In this work, we have developed Mo2C/N-doped carbon mesoporous heteronanowires (Mo2C/N–C MHNWs) with enhanced capacitive behaviour as high-performance anode materials for LIBs. With the heterostructure, the Mo2C nanocrystallites offer short paths for Li+ diffusion, while the N-doped carbon matrix facilitates fast electron transportation and buffers the volume change of Mo2C during the discharge/charge cycles. When evaluated as anodes for LIBs, the Mo2C/N–C MHNWs exhibited high capacity and high rate capability, as well as a long-term cycle life. In particular, a reversible capacity of 744.6 mA h g−1 was achieved in the first cycle, and 732.9 mA h g−1 was preserved after 700 cycles at a current density of 2 A g−1. The outstanding performance stems from fast kinetics enhanced by the pseudocapacitive effect, which was evidenced in the further analysis based on electrochemical impedance spectra and cyclic voltammetry. Our results elucidate the attractive Li+ storage performance of Mo2C-based nanocomposites, which may shed some light on the development of high-performance materials for energy storage and utilization.

Exploring efficient noble-metal free electrocatalysts for the hydrogen evolution reaction (HER) is one of the most promising pathways for facing the energy crisis. Herein, MoC–Mo2C heteronanowires composed of well-defined nanoparticles were accomplished via controlled carbonization, showing excellent HER activity, fast kinetic metrics and outstanding stability in both acid and basic electrolytes. In particular, the optimal one consisting of 31.4 wt% MoC displayed a low overpotential (η10 = 126 and 120 mV for reaching a current density of −10 mA cm−2), a small Tafel slope (43 and 42 mV dec−1) and a low onset overpotential (38 and 33 mV) in 0.5 M H2SO4 and 1.0 M KOH, respectively. Such prominent performance, outperforming most of the current noble-metal free electrocatalysts, was ascribed to the carbide surface with an optimized electron density, and the consequently facilitated HER kinetics. This work elucidates a feasible way toward efficient electrocatalysts via heteronanostructure engineering, shedding some light on the exploration and optimization of catalysts in energy chemistry.