The search for materials with superior electrocatalytic performance has attracted attention during the past few years aiming to identify a convenient material that works at a low overpotential with long-term stability. Herein, we introduce an innovative technique to fabricate two-dimensional BCN heterostructure nanosheets with various Cu:BCN weight ratios. The fabricated composites showed unique electrocatalytic properties for hydrogen evolution reaction (HER). The morphology and structure of the electrocatalysts were characterized using field emission scanning electron microscopy, Raman, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques. Remarkably, this study reveals the effect of electrochemical chronopotentiometry on facilitating the electrochemical exfoliation and hence enhancing the catalytic activity of the fabricated nanosheets. This effect was further confirmed via density functional theory (DFT) calculations, unveiling the effect of the formed oxide layer on the charge transfer process. The overpotential of the 0.125 Cu-BCN composite at a current density of -10 mA/cm 2 vs RHE is 50% lower than that of pristine BCN. These findings were also affirmed by the DFT calculations, which showed that incorporating copper on BCN has significantly reduced the G H* value of the HER and subsequently accelerates the kinetics of the reaction and the overall catalytic activity of the material.

There is a growing need for new techniques to synthesize metallic copper nanoparticles due to their remarkable use in many advanced technologies. Herein, a novel method to synthesize stable and nonagglomerated zero-valent copper nanoparticles (ZVCNPs) via the in situ formation of reduced graphene oxide (rGO) during the electrospinning process in the presence of polyvinylpyrrolidone as a carbon source is presented. X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance, transmission electron microscopy, and X-ray photoelectron spectroscopy techniques were used to investigate the morphology, structure, and composition of the fabricated materials. The synthesized ZVCNPs were coupled with TiO2 nanofibers and rGO to form an efficient photoactive material to photocatalytically produce hydrogen via water splitting, resulting in 344% increase in the hydrogen yield compared to that of TiO2 nanofibers. The density functional theory (DFT) calculations showed that the ZVCNPs enhance the charge transfer and lower the energy needed for photocatalytic water splitting. This study suggests a novel method for metallic copper stabilization and illustrates the effect of metallic copper as a catalyst for the in situ formation of rGO.

We report on the optimization of electrospun TiO2–CuO composite nanofibers as low-cost and stable photocatalysts for visible-light photocatalytic water splitting.

In the recent few decades, the demand for green sources of energy that are clean and sustainable became very essential to reduce the greenhouse and global warming problems. Consequently, there is an increasing demand to identify nonprecious, cheap bifunctional electrocatalysts for water splitting. Herein, nanosheets of different earth-abundant Ni, Co, Mn, and Fe combinations are electrodeposited over commercial Ti mesh and tested for the overall water splitting. The bare Ti mesh requires overpotentials of −486.6 mV at −10 mA cm −2 and 534.5 mV at 10 mA cm −2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. However, the electrodeposited catalysts show much higher catalytic activity for both HER and OER with overpotentials of −300 and 279 mV at −10 and 10 mA cm −2 , respectively, lowering the overpotential needed to drive the OER by 50%. Nevertheless, to enhance the electrocatalytic performance of the fabricated catalysts, they are phosphidized using different phosphorous precursors. The resulted NiCoMnFe−P catalysts exhibit much lower HER overpotential (−200 mV at −10 mA cm −2 ), which is 40% lower than that needed by the bare Ti mesh. For the overall water splitting, a cell voltage of 1.71 V is recorded to achieve a current density of 10 mA cm −2 . Lastly, the stability test of the overall device reveals very high stability with current retention of 90% over 22 h of continuous electrolysis. Furthermore, the synergy between the metallic components in the absence and presence of P is elucidated using density functional theory calculations, revealing optimized G H* and G Hd 2 O* for the HER reaction over the P-top site of the MnFeCoNiP catalyst. In addition, the calculations explain the superiority of the NiCoMnFe catalyst over the NiCoMnFeP counterpart for the OER.