Mott–Schottky Barrier Enabling High‐Performance Hydrazine‐Assisted Hydrogen Generation at Ampere‐Level Current Densities

Abstract

Local electron density manipulation can optimize the adsorption and desorption nature of catalysts leading to enhanced catalytic activity for water oxidation. Construction a Mott–Schottky barrier allows the electron transition in catalysts because of their different Fermi levels. Herein, a Pt@NiFc‐MOF Mott–Schottky heterojunction is constructed, in which electrons are transferred from NiFc‐MOF to Pt as triggered by the formed built‐in electric field at the interface. The as‐prepared Pt@NiFc‐MOF reveals exceptional performance toward the hydrazine oxidation reaction (HzOR), hydrogen evolution reaction (HER), and overall hydrazine splitting (OHzS) at ampere‐level current densities. The advanced nature of the configured Mott–Schottky heterojunction can also be further evidenced from a concept direct liquid N2H4/H2O2 fuel cell (Pt@NiFc‐MOF//Pt Net), yielding a maximum power density of 415.2 mW cm‒2 at 80°C and can work stably for 190 h at 500 mA cm‒2 (at 25°C). One more function of Pt@NiFc‐MOF is clarified as well, that is it can purify hydrazine‐rich wastewater from 718 to 6 ppb (less than the U.S. Environmental Protection Agency of 10 ppb) in 120 min at 500 mA cm‒2. This work represents a breakthrough in interface engineering of metal–organic frameworks (MOFs) toward industry‐level hydrogen generation and its beyond.

Metal–organic frameworks (MOFs) for hybrid water electrolysis: structure–property–performance correlation

“…Therefore, a series of MOFs have been employed to accelerate the dehydrogenation step of HzOR offering excellent performance. [82][83][84] Xi et al introduced a novel strategy involving metal node engineering to enhance the catalytic efficiency and stability of MOFs. 85 This involved the partial substitution of nickel with rhodium within Ni-BDC, resulting in the creation of an optimized catalyst termed NiRh 0.016 -BDC.…”

“…88 Huang et al conducted a fascinating study where they integrated platinum (Pt) with NiFc-MOF to create a Mott-Schottky heterojunction. 84 Their research revealed electron transfer from NiFc-MOF to Pt, facilitated by the built-in electric field at the interface. The resulting Pt@NiFc-MOF catalyst exhibited impressive performance in an N 2 H 4 /H 2 O 2 fuel cell, achieving a maximum power density of 415.2 mW cm À2 at 80 1C, with exceptional stability demonstrated for 190 hours of operation at 500 mA cm À2 (measured at 25 1C).…”

“…The resulting Pt@NiFc-MOF catalyst exhibited impressive performance in an N 2 H 4 /H 2 O 2 fuel cell, achieving a maximum power density of 415.2 mW cm À2 at 80 1C, with exceptional stability demonstrated for 190 hours of operation at 500 mA cm À2 (measured at 25 1C). 84 In a separate investigation, Sun et al combined NiCo-MOF with Mxene for electrocatalytic HzOR in both neutral and alkaline seawater environments. 82 Their study highlighted a significant enhancement in catalytic performance upon integrating Mxene with the MOF.…”

“…Therefore, a series of MOFs have been employed to accelerate the dehydrogenation step of HzOR offering excellent performance. 82–84…”

“…The resulting Pt@NiFc-MOF catalyst exhibited impressive performance in an N 2 H 4 /H 2 O 2 fuel cell, achieving a maximum power density of 415.2 mW cm −2 at 80 °C, with exceptional stability demonstrated for 190 hours of operation at 500 mA cm −2 (measured at 25 °C). 84…”