材料导报:能源(英文)最新文献

In the past tens of years, the power conversion efficiency of Cu(In,Ga)Se₂ (CIGS) has continuously improved and been one of the fastest growing photovoltaic technologies that can also help us achieve the goal of carbon emissions reduction. Among several key advances, the alkali element post-deposition treatment (AlK PDT) is regarded as the most important finding in the last 10 years, which has led to the improvement of CIGS solar cell efficiency from 20.4% to 23.35%. A profound understanding of the influence of alkali element on the chemical and electrical properties of the CIGS absorber along with the underlying mechanisms is of great importance. In this review, we summarize the strategies of the alkali element doping in CIGS solar cell, the problems to be noted in the PDT process, the effects on the CdS buffer layer, the effects of different alkali elements on the structure and morphology of the CIGS absorber layer, and retrospect the progress in the CIGS solar cell with emphasis on the alkali element post deposition treatment.

Currently the catalysis of hydrogen evolution reaction (HER) is mainly focused on the inherent electrocatalytic activity at relatively lower current densities while scarce at high current densities. Nevertheless, the latter is highly demanding in efficient mass-production of hydrogen. A SiO₂ nanospheres template-synthesis is used to prepare mesoporous molybdenum carbide nanocrystals-embedded nitrogen-doped carbon foams (mp-Mo₂C/NC). The material shows much more excellent catalytic activity than the non-etched Mo₂C/NC toward hydrogen evolution reaction (HER) in acidic medium. More interestingly mp-Mo₂C/NC still has larger overpotential than Pt/C at lower current densities, but possess remarkably smaller overpotential than the latter at higher current densities for much better electrocatalytic performance. An approach is developed to investigate the electrode kinetics by Tafel plots, especially with eliminating the diffusion effect, indicating that Pt/C and mp-Mo₂C/NC display different reaction mechanisms. At low current densities the former presents reversible reaction, while the latter shows mixed electrochemical polarization/reversible electrode process. In the region of higher current densities, the former becomes totally gas-diffusion controlled with large overpotential, while the latter can still retain an electrode polarization process for much lower overpotential at the same current density. Result endorses that the meso-porously structured mp-Mo₂C/NC plays a critical role in avoiding gas diffusion control-resulting large overpotential at high current densities. This work holds great potential for an inexpensive catalyst better than Pt/C in practical applications of mass-production hydrogen at high current densities, while clearly shedding fundamental lights on designs of rational HER catalysts for the uses at high current densities.

Cobalt-rich perovskite oxides play a paramount role in catalyzing oxygen evolution reaction (OER) on account of their acceptable intrinsic activity but are still challenging due to the high costs and undesired stability. In response to the defects, herein, the Mg-incorporated perovskite cobaltite SrCo_0.6Fe_0.3Mg_0.1O_3−δ (SCFM-0.1) is proposed as a novel earth-abundant and durable OER electrocatalyst. A well-consolidated cubic-symmetry structure and more active oxygen intermediates are enabled upon Mg substitution. Hence, the optimized SCFM-0.1 perovskite oxide achieves prominent OER electrocatalytic performance, that is, a low overpotential of only 320 mV at 10 mA cm⁻², a small Tafel slope of 65 mV dec⁻¹, as well as an outstanding durability within 20 h, substantially outperforming that of the pristine SrCo_0.7Fe_0.3O_3−δ and benchmark Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ and IrO₂ catalysts. The strong pH-dependent behavior associated with lattice oxygen activation mechanism for SCFM-0.1 catalyst is also confirmed. This work paves a unique avenue to develop cost-effective and robust perovskite cobaltites for efficient OER electrocatalysis.

Lithium-ion batteries (LIBs) and lithium-sulfur (Li–S) batteries are two types of energy storage systems with significance in both scientific research and commercialization. Nevertheless, the rational design of electrode materials for overcoming the bottlenecks of LIBs and Li–S batteries (such as low diffusion rates in LIBs and low sulfur utilization in Li–S batteries) remain the greatest challenge, while two-dimensional (2D) electrodes materials provide a solution because of their unique structural and electrochemical properties. In this article, from the perspective of ab-initio simulations, we review the design of 2D electrode materials for LIBs and Li–S batteries. We first propose the theoretical design principles for 2D electrodes, including stability, electronic properties, capacity, and ion diffusion descriptors. Next, classified examples of promising 2D electrodes designed by theoretical simulations are given, covering graphene, phosphorene, MXene, transition metal sulfides, and so on. Finally, common challenges and a future perspective are provided. This review paves the way for rational design of 2D electrode materials for LIBs and Li–S battery applications and may provide a guide for future experiments.

Earth-abundant copper-tin (CuSn) electrocatalysts are potential candidates for cost-effective and sustainable production of CO from electrochemical carbon dioxide reduction (eCO₂R). However, the requirement of high-overpotential for obtaining reasonable current, low Faradaic efficiencies (FE) and low intrinsic catalytic activities require the optimisation of the CuSn nanoarchitecture for the further advancement in the field. In the current work, we have optimised Sn loading on Cu gas diffusion electrodes (GDEs) by electrochemical spontaneous precipitation. Samples with various Sn loadings were tested in a three-chamber GDE reactor to evaluate their CO₂ reduction performances. The best performance of 92% CO Faradaic efficiency at a cathodic current density of 120 mA cm⁻² was obtained from the 20 min Sn deposited Cu₂O sample operated at −1.13 V vs. RHE. The electrocatalyst had ∼13% surface coverage of Sn on Cu GDE surface, and had Sn in oxide form and copper in metallic form. The catalyst also showed stable performance and was operable for >3 h under chronoamperometric conditions. The surface of the GDE reduces from Cu₂O to Cu during eCO₂R and goes further reconstruction during the eCO₂R. This study demonstrates the potential of Cu–Sn for selective CO production at high current densities.

Using clean solar energy to reduce CO₂ into value-added products not only consumes the over-emitted CO₂ that causes environmental problems, but also generates fuel chemicals to alleviate energy crises. The photocatalytic CO₂ reduction reaction (PCO₂RR) relies on the semiconductor photocatalysts that suffer from high recombination rate of the photo-generated carriers, low light harvesting capability, and low stability. This review explores the recent discoveries on the novel semiconductors for PCO₂RR, focusing on the rational catalyst design strategies (such as surface engineering, band engineering, hierarchical structure construction, single-atom catalysts, and biohybrid catalysts) that promote the catalytic performance of semiconductor catalysts on PCO₂RR. The advanced characterization techniques that contribute to understanding the intrinsic properties of the photocatalysts are also discussed. Lastly, the perspectives on future challenges and possible solutions for PCO₂RR are presented.