A New Porous Ni‐W Mixed Metal Phosphonate Open Framework Material for Efficient Photoelectrochemical OER

Abstract

Photoelectrochemical water oxidation or oxygen evolution reaction (PEC‐OER) at the semiconductor surfaces has attracted huge attention over the years as it plays key role for energetically demanding processes like fuel cells, water splitting, and rechargeable metal‐air batteries. Thus, development of sustainable, abundant and economical semiconductor nanomaterials as the catalyst for photoelectrochemical water oxidation reaction is very challenging in achieving high efficiency in the overall water splitting reaction. Herein, we report a new porous Ni−W mixed metal phosphonate material NiWPPA‐4 with open framework structure through simple hydrothermal route and its crystalline framework has been indexed into a new orthorhombic crystal with unit cell dimensions: a=14.5506 Å, b=17.6445 Å, c=20.1766 Å and α=β=γ=90°. NiWPPA‐4 has been successfully utilized for photoelectrochemical OER from moderately basic medium [1(M) KOH] under constant irradiation of 100 mWcm−1 light source. Semiconducting property together with nanoscale porosity in the Ni−W mixed metal phosphonate is responsible for photoelectrochemical OER in alkaline pH. To the best of our knowledge it is the first report on a mixed metal phosphonate material, which showed excellent catalytic activity in the photoelectrochemical OER. The onset‐potential of NiWPPA‐4 prepared over ITO coated glass was only −410 mV vs Ag/AgCl and the oxygen evolution rate is 275 μmol g−1. This study thus established efficient photoelectrochemical OER on porous mixed‐metal phosphonates and offer opportunities for the utilization of metal phosphonates as potential photocatalyst in the energy conversion processes.

Nanoporous Metal Phosphonate Hybrid Materials as a Novel Platform for Emerging Applications: A Critical Review

“…Bhaumik and co-workers reported a new porous Ni-W mixed metal phosphonate hybrids (NiWPPA-4) with open framework structure through simple hydrothermal synthesis. [124] The synthesized NiWPPA-4 hybrids behave as excellent catalyst with ultrahigh activities for photoelectrochemical water oxidation in alkaline pH. It was revealed that synergistic Ni-W bimetallic sites incorporated into hybrid framework with nanoscale porosity as well as remarkable semiconducting property are responsible for outstanding photoelectrochemical activity.…”

“…Heterogeneous catalysis plays a vital role in chemical transformations (e.g., energy related fields, asymmetric catalysis, and pharmaceutical synthesis), [119][120][121] where the development of low-cost and high-efficient catalysts has been considered to be the key to breaking performance bottlenecks. [122][123][124] The design of homogeneous catalysts not only needs to consider how to improve the activity and selectivity, but also needs to solve the difficulty of catalyst/product separation due to the same phase of catalysts with the reactants in a heterogeneous reaction. Thus, the design of highly stable, active, selective, and easily recyclable catalysts is very essential for sustainable chemical production.…”

“…These impressive properties make porous metal phosphonates promising as ideal carriers for heterogeneous catalysts. In this section, we reviewed the applications of porous metal phosphonates in heterogeneous catalysis, [119][120][121][122][123][124][125][126][127][128] which are specifically discussed based on metal sites, phosphonate functional groups, and their derivatives. A summary of the representative examples of catalytic porous metal phosphonates is presented in Table 5.…”

Design Strategies of Transition‐Metal Phosphate and Phosphonate Electrocatalysts for Energy‐Related Reactions

“…While currently, transition‐metal phosphate and phosphonate are acting as typical representatives of the burgeoning non‐noble metal electrocatalysts because they are low‐cost, environmentally benign, and present high stability, unique physicochemical characteristics and tunable multifunctionality. The presence of strong affinity between transition‐metal centers and phosphate/phosphonate ligands leads to the design of a large variety of transition‐metal phosphate and phosphonate materials [7–9] …”

“…The presence of strong affinity between transition-metal centers and phosphate/phosphonate ligands leads to the design of a large variety of transition-metal phosphate and phosphonate materials. [7][8][9] Transition-metal phosphate is a purely inorganic material composed of the binding of metal centers with phosphoric acid, which are prone to form a layered structure with an open framework. It possesses a good protonic conductivity and variable oxidation states of the metal species, which would enrich the redox behavior and thus is favorable when used as electrodes.…”