Interfacial Engineering of MoO₂‐FeP Heterojunction for Highly Efficient Hydrogen Evolution Coupled with Biomass Electrooxidation

Abstract

Simultaneous highly efficient production of hydrogen and conversion of biomass into value‐added products is meaningful but challenging. Herein, a porous nanospindle composed of carbon‐encapsulated MoO2‐FeP heterojunction (MoO2‐FeP@C) is proposed as a robust bifunctional electrocatalyst for hydrogen evolution reaction (HER) and biomass electrooxidation reaction (BEOR). X‐ray photoelectron spectroscopy analysis and theoretical calculations confirm the electron transfer from MoO2 to FeP at the interfaces, where electron accumulation on FeP favors the optimization of H2O and H* absorption energies for HER, whereas hole accumulation on MoO2 is responsible for improving the BEOR activity. Thanks to its interfacial electronic structure, MoO2‐FeP@C exhibits excellent HER activity with an overpotential of 103 mV at 10 mA cm−2 and a Tafel slope of 48 mV dec−1. Meanwhile, when 5‐hydroxymethylfurfural is chosen as the biomass for BEOR, the conversion is almost 100%, and 2,5‐furandicarboxylic acid (FDCA) is obtained with the selectivity of 98.6%. The electrolyzer employing MoO2‐FeP@C for cathodic H2 and anodic FDCA production requires only a low voltage of 1.486 V at 10 mA cm−2 and can be powered by a solar cell (output voltage: 1.45 V). Additionally, other BEORs coupled with HER catalyzed by MoO2‐FeP@C also have excellent catalytic performance, implying their good versatility.

Pseudo‐Bonding and Electric‐Field Harmony for Li‐Rich Mn‐Based Oxide Cathode

“…The electron cloud bias between the heterojunction interfaces is a solid evidence of the enhanced interaction and strong coupling effect, confirming the construction of a nanosized heterojunction at the phase interfaces. [ 20,28b,29 ] The intrigued phenomenon is well consistent with the Raman results. More importantly, it should be emphasized that the intimate contact between different phases would spontaneously form a heterojunction at grain boundaries.…”

“…In contrast, the DOS of S ‐LMO//LCO and LMO// S ‐LMO composites are larger than that of the single materials (Figure 7D,E) at the Fermi level, indicating that the electronic conductivity is significantly boosted for modified samples through engineering the characteristic heterostructure interfaces, and it is further verified by band gaps and the dispersion of energy diagram (Figure S8D,E, Supporting Information). [ 28a,29 ] In addition, the compatible contact between the different type of semiconductors can stimulate asymmetric charge distribution, thereby motivating the ISE effects as soon as the Fermi levels reach the balance through autonomous migration of carriers (Figure 7F,G), further certified by the averaged electrostatic potential of the composites (Figure 7H). More importantly, the electron transfer is from S ‐LMO to LMO (Figure 7G), which results in the electron accumulation on the LMO side and hole accumulation on the S ‐LMO side.…”

“…The electron–ion interaction and the exchange and correlation functions were described by projector augmented‐wave pseudopotentials and the Perdew–Burke–Ernzerhof (PBE) version of the generalized gradient approximation exchange‐correlation (GGA), respectively. [ 29 ] The kinetic energy cutoff of 400 eV was used for the wave functions expansion. Brillouin zone integration on the grid with 3 × 3 × 1 for the calculation.…”

2,5-Furandicarboxylic acid production via catalytic oxidation of 5-hydroxymethylfurfural: Catalysts, processes and reaction mechanism

“…After adding HMF to reach 100 mM, the required potential at the benchmark 10 mA cm À2 current density was just 1.269 V vs RHE with the corresponding Tafel plots of 125 mV dec -1 , demonstrating the highly thermodynamic and kinetic activities of the as-synthesized CoNW/NF catalyst. To our best knowledge, the result is still superior to the vast majority of the reported catalysts for electrooxidation of HMF, such as Ni 2 P NPA/NF (1.35 V vs RHE at onset) [133], Ni 3 S 2 /NF (1.35 V vs RHE at onset) [135], Co-P/CF (1.30 V vs RHE at onset) [134], hp-Ni (~1.35 V vs RHE at onset) [136], Ni x B/NF (1.38 V vs RHE at onset) [137], Nano-Cu foam (1.25 V vs RHE at onset) [146], NiCo 2 O 4 /NF (~1.36 V vs RHE for 10 mA cm À2 ) [140], NiFe LDH (1.25 V vs RHE at onset) [127], CuNi(OH) 2 /C (1.45 V vs RHE for 9.2 mA cm À2 ) [147], NiSe@NiO x (1.35 V vs RHE at onset) [148], and MoO 2 -FeP@C (1.323 V vs RHE at onset) [154]. For HER, the cathodic LSV curves exhibited no visible difference with and without HMF participation even the concentration of HMF up to 100 mM, contrasted to the situation of NF with 14 mV negative shift when 100 mM presented, indicating CoNW catalystequipped with a high preference for hydrogen formation rather than the possible reduction of aldehyde groups of HMF and intermediates.…”

Interface Engineering of Partially Phosphidated Co@Co–P@NPCNTs for Highly Enhanced Electrochemical Overall Water Splitting

“…In spite of the high electrocatalytic performance of the noble metal Pt, its rare reserves limit the practical application. [20] Some transition metal compounds including sulfides, [21][22][23][24][25] carbides, [26][27][28][29] nitrides, [30][31][32][33][34] and even non-metal carbon materials [35][36][37][38] have proved efficient for electrocatalytic HER; in addition, some transition metal phosphides (TMPs) [39][40][41][42][43] stand out for their hydrogenase-resembling structures, [44,45] yet they typically show lower conductivities because the high electronegativity of P restricts the electron delocalization in metal. [46] Besides, the surface oxidation of TMPs in ambient conditions would further block the active sites and hamper the activity.…”