Hydrogen Peroxide Versus Hydrogen Generation at Bipolar Pd/Au Nano-catalysts Grown into an Intrinsically Microporous Polyamine (PIM-EA-TB)

Abstract

Binding of PdCl42− into the polymer of intrinsic microporosity PIM-EA-TB (on a Nylon mesh substrate) followed by borohydride reduction leads to uncapped Pd(0) nano-catalysts with typically 3.2 ± 0.2 nm diameter embedded within the microporous polymer host structure. Spontaneous reaction of Pd(0) with formic acid and oxygen is shown to result in the competing formation of (i) hydrogen peroxide (at low formic acid concentration in air; with optimum H2O2 yield at 2 mM HCOOH), (ii) water, or (iii) hydrogen (at higher formic acid concentration or under argon). Next, a spontaneous electroless gold deposition process is employed to attach gold (typically 10- to 35-nm diameter) to the nano-palladium in PIM-EA-TB to give an order of magnitude enhanced production of H2O2 with high yields even at higher HCOOH concentration (suppressing hydrogen evolution). Pd and Au work hand-in-hand as bipolar electrocatalysts. A Clark probe method is developed to assess the catalyst efficiency (based on competing oxygen removal and hydrogen production) and a mass spectrometry method is developed to monitor/optimise the rate of production of hydrogen peroxide. Heterogenised Pd/Au@PIM-EA-TB catalysts are effective and allow easy catalyst recovery and reuse for hydrogen peroxide production. Graphical abstract

Effects of g-C3N4 Heterogenization into Intrinsically Microporous Polymers on the Photocatalytic Generation of Hydrogen Peroxide

“…Quantitative analysis of the hydrogen peroxide concentration was performed following a literature method. 61 Briefly, H 2 O 2 was reacted with para-nitrophenyl boronic acid to give para-nitrophenol, which was quantified by mass spectrometry coupled to HPLC (Automated Agilent QTOF; see details in the Supporting Information).…”

TiO2 nanocrystal rods on titanium microwires: growth, vacuum annealing, and photoelectrochemical oxygen evolution

“…The initial value of typically −0.4 μA is typical for the background concentration of 0.2 mM oxygen in aqueous solution. 33 Due to oxygen evolution, this value increases during the experiment reaching approx. −1.3 μA.…”

Artificial Formate Oxidase Reactivity with Nano-Palladium Embedded in Intrinsically Microporous Polyamine (Pd@Pim-Ea-Tb) Driving the H2o2 – 3,5,3’,5’-Tetramethylbenzidine (Tmb) Colour Reaction

“…Hydrogen peroxide detection. Hydrogen peroxide quantification was carried out following a previously reported method [21]. Briefly, H 2 O 2 reacts with p-nitrophenol boronic acid stoichiometrically in alkaline conditions and produces p-nitrophenol.…”

“…1A shows an illustration of the Clark probe with the catalyst (immobilised on a Nylon disk substrate) attached to the Teflon membrane outer surface. An applied potential of À0.7 V vs Ag/AgCl allows oxygen detection and an applied potential of + 0.6 V vs Ag/AgCl allows hydrogen detection [21].…”

“…2- [20] is reduced with borohydride. In a recent report [21], it was shown that Pd@PIM-EA-TB was produced with typically 3 nm diameter palladium nanoparticles embedded into the polymer film. In the presence of formic acid, these nanoparticles form hydrogen peroxide (in the presence of low concentration of HCOOH) and hydrogen (in the presence of higher concentrations of HCOOH).…”