Low-Cost Ni₂P/Ni_0.96S Heterostructured Bifunctional Electrocatalyst toward Highly Efficient Overall Urea-Water Electrolysis

Abstract

Water splitting is a sustainable approach for production of hydrogen to fuel some clean energy technologies. This process, unfortunately, has been significantly impeded by the puzzles in either the efficient but economically unaffordable noblemetal-based catalysts or the low-cost but kinetically sluggish abundant-element-based catalysts. Particularly, the discovery of efficient bifunctional catalysts that can simultaneously trigger the reactions of both anode and cathode for overall water splitting still remains as a grand challenge. Herein, a novel low-cost bifunctional Ni 2 P/Ni 0.96 S heterostructured electrocatalyst, which is active for both the urea oxidation reaction at the anode and the hydrogen evolution reaction at the cathode, is innovated for high-efficiency overall splitting of urea-rich wastewater. A systematic configuration of a Ni foam (NF)-supported Ni 2 P/Ni 0.96 S catalyst electrode exhibits superior catalytic activity and stability. The Ni 2 P/Ni 0.96 S/NF||Ni 2 P/Ni 0.96 S/NF cell needs only 1.453 V to reach a current density of 100 mA/cm 2 in basic urea-containing water, while it is 1.693 V for a reference noble-based Pt/ C/NF||IrO 2 /NF electrolysis cell. This work therefore not only contributes to develop a low-cost, high-efficiency, bifunctional electrocatalyst but also provides a practically feasible approach for urea-rich wastewater treatment.

Heteroatom‐Doping of Non‐Noble Metal‐Based Catalysts for Electrocatalytic Hydrogen Evolution: An Electronic Structure Tuning Strategy

“…discovered that the P‐doped NiS can form low‐cost Ni 2 P/Ni 0.96 S heterostructured bifunctional electrocatalyst to catalytic an overall urea‐water electrolysis reaction, owing to the boosted reactivity toward both HER and urea oxidation reaction (UOR). [ 119 ]…”

Progress and Perspectives in Photo‐ and Electrochemical‐Oxidation of Biomass for Sustainable Chemicals and Hydrogen Production

“…The unique heterostructure could also provide lattice defects for more active sites and expedite gas releasing and electrolyte diffusion. [293] In summary, biomass electrolysis has lower thermodynamic requirements compared to water electrolysis, leading to low ΔE eq and high H 2 production efficiency, however the kinetics are also sluggish due to the multiple electron transfer process. Electrocatalyst design need to take into consideration of the chemical structure of different biomass substrates.…”

“…[290] Hybrid systems can have more active sites without sacrificing the electronic conductivity. [291][292][293][294] For example, Li et al designed CoS 2 /MoS 2 Schottky heterojunctions to manipulate the surface charge distribution for synergistically boosting the adsorption and scission of chemical bonds of urea molecules. [285] The resulted electrode showed superior activity toward urea electrolysis, with a cell voltage as low as 1.29 V to achieve a stable current (60 h) of 10 mA cm −2 .…”

Boosting hydrogen generation by anodic oxidation of iodide over Ni–Co(OH)2 nanosheet arrays

“…3 In this regard, replacing OER with more favorable oxidation reactions at anode has triggered a lot interests, such as tetrahydroisoquinolines oxidation, urea oxidation reaction (UOR), amine oxidation, and N 2 oxidation. [4][5][6][7][8][9][10][11][12][13][14][15] Among them, (UOR) with low equilibrium potential of 0.37 V has been regarded as promising alternative to achieve energy-saving hydrogen generation and great process has been made. [16][17][18] Unfortunately, UOR also undergoes sluggish kinetics due to its multi-electron process and requires highly active electrocatalysts to accelerate its reaction rate.…”