Co and Fe Codoped WO_2.72 as Alkaline‐Solution‐Available Oxygen Evolution Reaction Catalyst to Construct Photovoltaic Water Splitting System with Solar‐To‐Hydrogen Efficiency of 16.9%

Abstract

Oxygen evolution electrode is a crucial component of efficient photovoltaic‐water electrolysis systems. Previous work focuses mainly on the effect of electronic structure modulation on the oxygen evolution reaction (OER) performance of 3d‐transition‐metal‐based electrocatalyst. However, high‐atomic‐number W‐based compound with complex electronic structure for versatile modulation is seldom explored because of its instability in OER‐favorable alkaline solution. Here, codoping induced electronic structure modulation generates a beneficial effect of transforming the alkaline‐labile WO 2.72 (WO) in to efficient alkaline‐solution‐stable Co and Fe codoped WO 2.72 (Co&Fe‐WO) with porous urchin‐like structure. The codoping lowers the chemical valence of W to ensure the durability of W‐based catalyst, improves the electron‐withdrawing capability of W and O to stabilize the Co and Fe in OER‐favorable high valence state, and enriches the surface hydroxyls, which act as reactive sites. The Co&Fe‐WO shows ultralow overpotential (226 mV, J = 10 mA cm −2 ), low Tafel slope (33.7 mV dec −1 ), and good conductivity. This catalyst is finally applied to a photovoltaic‐water splitting system to stably produce hydrogen for 50 h at a high solar‐to‐hydrogen efficiency of 16.9%. This work highlights the impressive effect of electronic structure modulation on W‐based catalyst, and may inspire the modification of potential but unstable catalyst for solar energy conversion.

Ultra‐Durability and Enhanced Activity of Amorphous Cobalt Anchored Polyaniline Synergistic towards Electrocatalytic Water Oxidation

“…Solar power is the major renewable natural resource thus, solar irradiation in water electrolysis become the new energy pathway [54–56] . Conventional solar panel was utilized to generate maximum voltage of 5.83 V, because of high open circuit voltage and current density sufficient voltage was produced for water splitting.…”

Tuning the Electronic Structure of Tungsten Oxide for Enhanced Hydrogen Evolution Reaction in Alkaline Electrolyte

“…Thus, Structure engineering strategies were also utilized to tune the catalytic behavior [26] . For example, the modulated electronic structure and particle morphology of Co and Fe codoped WO 2.72 enhanced the OER performance [27] . Ni 17 W 3 ‐WO 2 heterogeneous metal‐metal oxide system accelerated the alkaline HER activity by facilitating water dissociation and hydrogen generation in alkaline solution.…”

Electrodeposited Trimetallic NiFeW Hydroxide Electrocatalysts for Efficient Water Oxidation

“…The results illustrated that high‐ valence Co and Fe provided electrons to W to lower its valence state, increasing the electron‐withdrawing capability and generating more surface hydroxy groups, which act as the active sites for water oxidation. The lower valence state of W thus enabled excellent stability under alkaline conditions [32] . Single‐atom W‐doped Ni(OH) 2 demonstrated an outstanding OER performance owing to the presence of W 6+ states as reactive sites for higher OH − adsorption to generate O radicals and O−O coupling, ultimately promoting the water oxidation process on Ni(OH) 2 .…”