One-Step Synthesis of a Self-Supported Copper Phosphide Nanobush for Overall Water Splitting

Abstract

Developing cheap, stable, and efficient electrocatalysts is of extreme importance in the effort to replace noble metal electrocatalysts for use in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). We report a three-dimensional self-supported Cu 3 P nanobush (NB) catalyst directly grown on a copper mesh via a one-step method. This nanostructure exhibits a superior catalytic activity of achieving a current density of 10 mA cm –2 at 120 mV and exhibits a long-term stability in acid solutions. It shows a Tafel slope of 72 mV dec –1 and an onset potential of −44 mV. This catalyst displays a good catalytic activity in basic electrolytes, reaching a current density of 10 mA cm –2 at the overpotential values of 252 and 380 mV for HER and OER, respectively. The bifunctional Cu 3 P NB/Cu catalyst exhibits better catalytic performances than the Pt/C and IrO 2 catalysts in a two-electrode electrolyzer for overall water splitting.

3D‐Graphene Decorated with g‐C3N4/Cu3P Composite: A Noble Metal‐free Bifunctional Electrocatalyst for Overall Water Splitting

“…(details data of all individual samples are listed in Table S1) The Tafel plots (Figure b) are calculated from the linear region of the Tafel equation (η= blogj+a; where b is the Tafel slope, η is the overpotential, j is the current density and a is a constant). The Tafel slope for Pt/C (20 wt%) is 31 mV/dec which is quite similar to the earlier reports and that of to 3DG‐Mix, Mix, 3DG−Cu 3 P were found to be 45, 90, 110 mV/dec; respectively. These values are much better than previously reported Cu 3 P or g‐C 3 N 4 based electrocatalyst (shown in Table S5).…”

“…(Figure d–i) The structure and morphology of the 3DG‐Mix sample are characterized via SEM (Figure b) and high‐resolution TEM (HR‐TEM) shown in Figure c where lattice fringes of individual material are clearly been observed. The lattice fringes of 0.24 nm, 0.20 nm, 0.17 nm correspond to the plan of (112), (300) and (220) of hexagonal Cu 3 P and that of 0.33 nm for the graphitic layers refers to (002) plane of both graphene and g‐C 3 N 4 . Nevertheless, it is very difficult to visualize the g‐C 3 N 4 nanosheet lattice spacing separately in the 3DG‐graphene matrix due to the presence of a very low amount of g‐C 3 N 4 compared to graphene.…”

“…Figure j, shows the XRD diffraction peak of Cu 3 P, g‐C 3 N 4 , Mixture of g‐C 3 N 4 and Cu 3 P (Mix), 3DG and 3DG‐Mix samples, respectively. Cu 3 P shows the diffraction peak at 31.10, 36.21, 39.60, 42.01, 45.02, 46.59, 53.80, and 59.2 which corresponds to the planes of (111), (112), (202), (211), (300), (113), (220), (222) for hexagonal Cu 3 P . In case of g‐C 3 N 4 two characteristic sharp peaks at 13.0 and 27.5 degrees are corresponding to the planes of (100) and (002) which could be attributed to the in‐plane structural motif of the continuous heptazine or triazine network and interlayer stacking, respectively .…”

“…The Tafel slope of 3DG‐Mix is closer to Pt/C (20 wt%) and indicating that superior catalytic activity. Thus it is suggesting that HER process takes place through Volmer‐Heyrovsky reaction mechanism where electrochemical desorption step (or discharge step) is the rate‐limiting step . To examine the interfacial properties, as well as electrode kinetic for superior HER performance of the catalysis, the electrochemical impedance spectra (EIS) test, is performed.…”

“…Considering increasing global energy demands and the major environmental issues, climate change resulting primarily from fossil fuel utilization instigate research efforts in the exploration of various catalytic systems for the conversion and storage of renewable and carbon‐neutral energies . Catalytic water splitting to generate hydrogen as a fuel has been considered as the sustainable and remarkable approach to offer a promising strategy and has already captured a prime place among the existing scientific community . For efficient water splitting, the two crucial reactions: cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) can reduce the energy barrier and minimize the required overpotential via introducing the highly efficient electrocatalyst .…”