Multifunctional photo‐electrocatalysts of copper sulfides prepared via pulsed laser ablation in liquid: Phase formation kinetics and photo‐electrocatalytic activity

Abstract

Summary Designing a highly efficient and less expensive electrocatalyst for electrolyzers and fuel cells is of great importance to creating a sustainable future energy source. Herein, we applied a unique and extremely facile pulsed laser ablation in the liquid synthesis route for the fabrication of phase‐engineered CuxSy nanospheres. The multifunctionality of these catalysts was assessed by examining the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and methanol oxidation reaction (MOR). As a result, low overpotentials of 390 mV (HER) and 440 mV (OER) were achieved for sulfur‐rich and copper‐rich samples in alkaline media, respectively. Furthermore, the high selectivity of Cu over methanol and the high number of electrochemically accessible active sites equal to 7.9 × 1016 promoted the MOR with a current density of 28.3 mA/cm2 at the vertex potential. It is worth emphasizing that in this research, we consider the electrocatalyst's initial electrocatalytic water decomposition function to gain a better understanding of the photoelectrocatalytic behavior. Using a beneficial photo‐assisted electrochemical method, a high OER catalytic activity was obtained under light irradiation due to the large light absorption coefficients of the synthesized electrocatalysts, which facilitated electron transfer at the electrode‐electrolyte interface.

Moving beyond Ti2C3Tx MXene to Pt-Decorated TiO2@TiC Core–Shell via Pulsed Laser in Reshaping Modification for Accelerating Hydrogen Evolution Kinetics

“…Thus, the obtained Tafel slope values for the synthesized electrocatalysts are 62.45, 54.03, 64.05, 124.49, 96.24, and 391.17 mV/dec for traditional Pt/C, Pt/TiO 2 @TiC/Pt-5, Pt/TiO 2 @TiC/Pt-10, Pt/TiO 2 @TiC/Pt-20, Pt NPs, and TiO 2 @TiC, respectively (Figure c). Notably, the significant enhancement in the HER activity under light irradiation could be due to the semiconductor behavior of the electrocatalysts, which possess the characteristics of optical and electronic properties, including band energies and charge carriers. , Furthermore, the faster charge-transfer kinetics confirmed that the optimal Pt/TiO 2 @TiC/Pt-5 sample shows the lowest R ct value compared with other electrocatalysts in Figure d, resulting in higher hydrogen evolution. However, the observed band energy-gap values for Pt/TiO 2 @TiC/Pt-5, Pt/TiO 2 @TiC/Pt-10, Pt/TiO 2 @TiC/Pt-20, and TiO 2 @TiC from the XPS spectra are 3.20, 3.29, 3.35, and 3.43 eV, respectively, indicating that the narrow band gap of Pt/TiO 2 @TiC/Pt-5 can absorb more visible light (Figure e–h).…”

Data-Driven Predetermination of Cu Oxidation State in Copper Nanoparticles: Application to the Synthesis by Laser Ablation in Liquid

“…Target surface properties like roughness, purity, and contamination are generally unknown. Concerning the choice of using the % of O + Cl + CN + S in solvent and solutes, this is based on the strong empirical evidence in the literature that any of these elements can react with Cu. ,− Hence, this feature was preferred over the % of each single chemical group (O, Cl, CN, S but also C, H, and N) to reduce the already cumbersome list of parameters and facilitate the discovery of mutual correlations with the other features whose role remains more obscure.…”

“…Nanomaterials play a major role in the global challenge toward the solution of the environmental crisis and the development of a circular economy, as indicated by the United Nations Sustainable Development Goals and the European Union Circular Economy Action Plan. , Among the nanomaterials which are indispensable components for the most advanced technologies integrated with renewable energy sources, , copper-based nanoparticles (NPs) have gained substantial attention. − As other transition metals, Cu is earth-abundant, and its oxides are considered inert, nontoxic, stable, and low-cost. − Copper oxides are intensely studied as heterogeneous catalysts for their good reactivity and selectivity in numerous oxidation and reduction reactions. , Metallic copper NPs and copper oxide NPs doped with metallic clusters are the most selective electrocatalysts for the conversion of CO 2 into chemical feedstock, possibly powered by renewable energy. − CuO NPs are versatile p-type semiconductors because of the ease of manipulation of its band gap by quantum confinement, and CuO was one of the earliest proposed wide-bandgap oxides for all-oxide photovoltaic cells. , Copper oxide NPs emerged as a prominent material in solar thermal conversion research . Nano-Cu 2 O is suitable for the absorbing layer of all-oxide photovoltaic cells, − for cathodes in dye-sensitized solar cells, as self-healing photocathode in photoelectrochemical hydrogen evolution, or the hole-transport layers in perovskite solar cells, while copper sulfides are efficient photo- and electro-catalysts . The interest in Cu-based NPs goes beyond energy materials because the implementation in supercapacitors, gas sensors, or nanofluids is in an advanced stage, and Cu NPs are among the most studied antimicrobial agents in the fight against antibiotic-resistant bacteria, which constitute one of the main global challenges for humankind. , …”

“…With LAL, Cu, Cu 2 O, CuO, Cu 2 S, and CuCN NPs have been synthesized using a metallic Cu target while varying the laser source, setup, solvent, and solutes. ,− Unfortunately, the LAL of Cu targets usually produces a mixture of these different phases. Picking just a specific compound is a rather empirical endeavor based on changing the LAL synthesis parameters, which is particularly complex in the case of compounds with intermediate oxidation states such as Cu 2 O.…”

“…13 Nano-Cu 2 O is suitable for the absorbing layer of all-oxide photovoltaic cells, 14−16 for cathodes in dye-sensitized solar cells, 17 as self-healing photocathode in photoelectrochemical hydrogen evolution, 18 or the hole-transport layers in perovskite solar cells, 19 while copper sulfides are efficient photo-and electro-catalysts. 20 The interest in Cu-based NPs goes beyond energy materials because the implementation in supercapacitors, 21 gas sensors, 22 or nanofluids is in an advanced stage, 23 and Cu NPs are among the most studied antimicrobial agents in the fight against antibiotic-resistant bacteria, which constitute one of the main global challenges for humankind. 24,25 It is thus of utmost importance to develop new sustainable and efficient synthetic technologies for the realization of the type of Cu nanocrystals exploited in the next-generation catalytic processes, photovoltaic devices, environment remediation protocols, and any other technology for a sustainable future.…”