Sulfur and Nitrogen Dual-Doped Molybdenum Phosphide Nanocrystallites as an Active and Stable Hydrogen Evolution Reaction Electrocatalyst in Acidic and Alkaline Media

Abstract

Sulfur and nitrogen dual-doped molybdenum phosphides (MoP/SN) are synthesized via a (thio)­urea-phosphate-assisted strategy in which the reductant (thio)­urea acts as S and N source and phosphoric acid provides the P atom. The MoP/SN nanoparticles are generated by in situ phosphidation of indigenously synthesized ammonium phosphate-coated P-doped MoS x nanoparticles in a hydrogen atmosphere. Then, MoP/SN is anchored on graphene to obtain a hybrid electrocatalyst (MoP/SNG) that exhibits high activity and stability for electrochemical hydrogen evolution from water in both acidic and basic electrolytes, outperforming most MoP-based electrocatalysts reported in the literature. The dual doping and hybridization with graphene enhance electron conductivity of MoP and stabilize small MoP nanoparticles to increase activity and stability, especially in acid electrolytes.

Ultrafine MoP Nanoparticles Well Embedded in Carbon Nanosheets as Electrocatalyst with High Active Site Density for Hydrogen Evolution

“…[22] The TEMimages of MoP/NPG reveals that MoP NPs on glucose-derived nanosheets have a better dispersion than that of reduced graphene oxide as reported in previous works. [11] HRTEM of MoP/NPG nanosheets ( Figure 2d 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 elemental mapping was recorded to further confirm the elemental distribution. As seen, the elements of C, N, P and Mo have a good distribution on carbon nanosheets.…”

“…Another broad peak located at 134.2 eV is attributed to P−O which is oxidized by the air . In Figure d, the XPS spectrum of N 1s has four peaks at 394.4, 398.1, 399.0 and 400.7 eV, which are assigned Mo−N, pyridinic‐N, pyrrolic‐N and graphitic‐N, respectively ,. Additionally, based on the integrated peak areas, the atomic content of Mo and P are 3.88 % and 4.67 %, suggesting the excess of P as heteroatoms are incorporated in carbon nanosheets.…”

“…Therefore, researchers have put a great efforts on MoP‐based catalysts to increase the active sites, such as MoP (NPs) on reduced graphene oxide, MoP nanoarrays and MoP nanosheets, etc . Jae Sung Lee successfully synthesized S and N dual‐doped molybdenum phosphides (MoP/SN) on reduced graphene oxide (RGO) . However, the complicated synthetic approach and the using of RGO could result in high cost.…”

“…[10] Jae Sung Lee successfully synthesized S and N dual-doped molybdenum phosphides (MoP/SN) on reduced graphene oxide (RGO). [11] However, the complicated synthetic approach and the using of RGO could result in high cost. Furthermore, the smaller MoP NPs can further enhance the performance of HER.…”

Molybdenum‐Based Carbon Hybrid Materials to Enhance the Hydrogen Evolution Reaction

“…[121] designed and fabricated3 Ds elf-supported hybrid electrodes, few-layered N-P co-doped carbon-encapsulated ultrafine MoP nanocrystal/MoP cluster hybrids on carbon cloth( FLNPC@MoP-NC/MoP-C/CC) ( Figure 14). Lee's group [122] developed sulphurnitrogen dual-doped molybdenump hosphides (MoP/SN) on reducedg raphene oxide (MoP/SNG)t hat exhibitedh igh catalytic activity (Tafel slopes:3 1mVdec À1 in acidic conditions, 54 mV dec À1 in alkaline condition) and good stability for electrochemical hydrogen evolution in both acidic and alkaline electrolytes. Then, MoO 3 -micro-rods (MRs) were growno nP ANI/CC to prepare MoO 3 -MRs/PANI/CC using the hydrothermal reaction of (NH 4 ) 6 Mo 7 O 24 with tartaric acid (C 4 H 6 O 6 ).…”